No it isn't.
I shot both systems simultaneously (Sony FF and Fuji) and lens for lens the Fuji is most definitely smaller and lighter, and more importantly has much better ergonomics for my taste.
XF 35/1.4 significantly smaller and lighter than the FE 55/1.8; same FOV, near as makes no difference DOF... Fuji's lens has an aperture ring.
XF 18-55mm smaller, same weight, better construction; more range, same or better DOF. And that's not even comparing it to the Zeiss 24-70mm f4 since optically I'd say that's the more fair comparison.
Add in the fact that the ISO performance between the standard a7/ii is worse than the X-TransIII and DOF becomes the only equivalent measure between the lenses.
I think it's great that Sony gives you the options to be flexible with numerous bodies and some options with their smaller lenses, but without going 3rd party there aren't a whole lot of options for smaller lenses on their system. They've also been pretty clear lately that they're far more interested in developing their high end line and their smaller/lighter FF kit is clearly not a priority.
XF 35 f1.4 -> FE 50 f1.8
XF 18-55 -> FE 28-70
size differences are negligible
Why should it have been? By doing that, I would have been comparing a full frame to a full frame and the point is to compare a full frame to a crop.
Also, a Sony A7 used is around $700~800. That's twice what this crop cost used. They're otherwise the same size. Similar features, similar ISO range, etc. But again at twice the cost. And it forces me to use full frame size lenses, which are larger. For me, that's not worth it. And for me, Sony's color reproduction isn't as good as Canon or Fuji, but that's personal to me. I also don't want Sony-Star-Eater problems.
I'd rather compare a Fuji crop to a Sony full frame, than a full frame to full frame for the purpose of this thread. But I don't have Sony.
I do have Canon full frame and Fuji crop, so that's what I'm using and not just re-stating something I've read (not implying you are doing that, but there are many in these threads that spout off about full frame this, or crop that, and they haven't touched any of these cameras nor have both systems, etc, but they "heard").
Sony has the FE 85 F1.8, yes, and it's small. It's small because it's F1.8. The moment it becomes F1.4 or faster, it gets larger. But almost everything else is not with Sony. Both systems have small lenses. So this doesn't really argue much. What I would be doing is getting the same lenses, but designed for full frame, which are much larger. A Rokinon 35mm F1.4 for the A7 for example is a big lens, compare that to the Rokinon 21mm F1.4 for a crop, it's significantly smaller (and would be for a Fuji or Sony E mount, not the A7). This applies to all the fast standard primes from third parties if you want to really compare sizes stuff. Full frame stuff is bigger for these kinds of lenses. This is another reason I was swayed to a different system, as I was strongly considering Sony. But Sony's E-Mount cameras were not very attractive to me, and I can get the same third party lenses for the E mount as the Fuji. So the only thing to compare there are the cameras themselves.
For my Fuji crop, I have a 12mm F2 (18mm FOV FF EQ), 21mm F1.4 (32mm FOV FF EQ), 50mm F1.2 (75mm FOV FF EQ) & 85mm F1.4 (127mm FOV FF EQ) and they're small lenses (the 85 is the largest and is an old design, they obviously just built the mount adapter into the lens extending it, it's a larger lens than the Canon mount because of this as they added registration distance, the 85 is an old lens with full frame and old dSLR registration distances built in, not a good lens for this example; but, the rest are 3 inches or less in size and are designed for mirorrless crop, and are tiny and light weight and that's the point here). Again, understanding that the Rok 85mm is not a mirrorless/crop designed lens, it's an older design and is larger.
No, it isn't.
Anyone can compare a crop designed lens to a full frame designed lens:
The Rokinon 35 F1.4 (710 grams, 3.27 x 4.39") & Rokinon 21 F1.4 (275 grams, 2.53 x 2.66")
Put them on a Sony A7 (your suggestion) and Fuji XT body and compare size as the cameras are essentially the same size, and all you have left is the obvious huge difference in lens size (see above). Do this for several lenses, any of them really. Do it for equivalent FOV lenses and same or similar speed. So take a look at the full frame designed lenses for that A7 for 17~18mm F2 (doesn't exist, so you have to go slower and wider with a 14 F2.8 which is still bigger than a 12mm F2), 35mm F1.4, 85mm F1.4 (this is huge compared to a 50mm on a crop) and 135mm F2 (85mm F1.4 on crop, the 135 is significantly larger still). All the full frame lenses here are bigger, heavier, longer.
Sony E mount, using small lenses, would by a smaller system than Sony A7 with full frame lenses, equivalent focal lengths and f-stop speed. Not just Fuji.
The only thing out there that is a "full frame lie" is that mirrorless full frame is smaller than dSLR full frame. That is true, because they do not significantly weigh less or are significantly smaller in volume/size. That's full frame to full frame, and that is a known minsconception that mirrorless full frame is "smaller" because it's really not with the big lenses.
But crop mirrorless is smaller. And is lighter. There's no lie there, no misconception. It's clearly measured out and presented everywhere, for both Sony & Fuji.
Here's my full frame ultrawide setup, and my crop ultrawide setup. The only way to get my ultrawide smaller on my full frame is to get an old Tokina 17mm F3.5 prime and it's small and light, so it would be an equivalent size to the 12mm F2 here. But then you're left with the obvious body size and weight difference. So no matter how you slice it, the crop system is smaller and lighter, even if I swap out a lens to a 17mm slow prime to be truly equivalent.
I think the spirit of this thread is that there was a time when full frame was clearly, significantly better and had more options (especially on the wide end) in lenses. But that time is gone. Today, there's plenty of excellent glass and wide options for crops. There are small, mirrorless crops that are truly smaller than full frame systems even if the body is the same size or close, because the full frame lenses are significantly larger for the fast stuff. The spirit of the thread is that you don't have to have a full frame to achieve specific things that were a full frame thing of the past (such as super shallow DOF with short lenses due to fast focal-ratios, and ultrawide focal lengths, also fast focal-ratios). Someone who really has to ask other people if they should go full frame or crop and have no body of work to present to show what they're even doing prior to the question, probably doesn't need full frame.
You simply don't have to have full frame for the sake of the "magic bullet" that full frame was many years ago. Today's crop systems are excellent and truly smaller. There's a reason a lot of people even went to Micro 4/3's to get smaller, lighter kit because today's smaller crop sensors are excellent.
equivalency can and should be debated.
When comparing lenses, grabbing the largest isnt very practical, and third party for comparisons can go both ways. Voigtlander 40mm F1.2 is a very small lens for FULL FRAME. Equivalency would be something like 25mm f0.95 aps-c. I personally shoot with a third party CV 35mm f1.7, which is a very small lens.
so, in that way, equivalency can get messy.
there's a little more to equivalency, in that if you were to shoot said brand, HOW would you shoot it. What would you be comfortable with?
Some folks love carrying around f2.8 zooms from 16-200mm, that can be their preferred shooting style. For people that like smaller options, make now mistake about it, Sony FF does offer small and light lenses if you're actively looking for them.
I'm growing on 35/85 combo, and the lenses picked out are smallish, ranging from 120g to 350g. It's really manageable. I dont really do 24 that often, but I do have the OM 24 f2.8 that's a dslr pancake lens, still pretty small when adapted.
samyang 12mm f2, can be comparable to batis 18 or loxia 21, but will cost a lot more. One has AF the other is MF. Loxia probably even smaller than that SY.
as far as star eatery, generally an issue with high end high megapixel bodies. The older 7 and 7R and 7s dont have problems. It was introduced into late firmware. Similar to fuji, sony has released firmware fixes and gave extra functionality, so I wouldnt count out a fix for it.
Back to the size issue, it's about looking for a small sized kit, if you want one for either system, you can certainly find it. Fuji's smallest kit, will likely be smaller than Sony's smallest kit, but it wont be drastic.