user8291: As title above, what is the point of playing 3.Nc3 (before d2-d4) after 1.e4 c5 2.Nf3 d6? Compared to the “normal” 1.e4 c5 2.Nf3 d6 3.d4?
[fen ""]

[Variant "Standard"]
[ECO "B50"]
[Opening "Sicilian Defense"]

1. e4 c5 2. Nf3 d6 3. Nc3 { Less common move } (3. d4 { Usual move })


user19236: Does it make sense though if white hates the sicilian 1. e4 c5 2. Nf3 d6 3. d4 cd 4. Nxd4 Nc6? Usually this move order leads to some Rauzer system after 5. Nc3 Nf6. 
The move order with 4... Nc6 gives White just the extra option to play some kind of Maroczy bind, and after 1. e4 c5 2. Nf3 d6 3. Nc3 Nf6 4. d4 cd4 5. Nc6 White ends up in the Rauzer anyway. 
I guess some people play 3. Nc3 against 2... d6 only, because they are playing it against 2... Nc6. After 1. e4 c5 2. Nf3 d6 3. Nc3, Black has no much additional options (except maybe 3... a6). 
After 1. e4 c5 2. Nf3 Nc6 3. Nc3 White manages to avoid the Sveshnikov, since there is no useful waiting move for black which still leads to Sveshnikov. 

user19250: Najdorf players will have to go either 3. ...Nf6 or 3. ...a6. After the latter, White may make a move after which he deems ...a6 sligtly premature, such as 4. g3 (without saying that this will lead to an advantage for white over the Open Sicilian). I played 4. a4 once and got a good position after ... Nf6 5. e5 dxe5 6. Nxe5 Nbd7 7. Nc4 Nb6 8. a5 with a bind on the Q-side. 
After the former, there is 4. e5!? as well which is more dangerous than it looks and can easily throw an unprepared opponent off guard. The line is a specialty of 2700 player Mamedov.

user18809: If White is not willing to play a Maroczy formation (with c4), then Nc3 will eventually be played in almost any variation. Black has no clear way of preventing d2-d4 on the next move (3...e5 kind of sucks)
On the other hand, White may want to wait for Black's move before deciding whether to push d2-d4 or maybe go for a different variation against certain Black's responses (for example a closed Sicilian after 3...e6 4.g3

user12873: It basically just stalls for a move before 100% committing to the open Sicilian. For example, suppose you were playing White and hated facing this Sicilian (1.e4 c5 2. Nf3 d6 3.d4 cd 4.Nxd4 Nc6). You could use the move order you described and after 3.Nc3, only play 4.d4 if your opponent doesn't play 3...Nc6. If they do play 3...Nc6, then go for some Closed Sicilian.
Also in online bullet some people have done the 3.Nc3 move order against me because it takes half a second to realize what's happening and then play 3...Nf6 instead of 3...cd.

8291: <p>As title above, what is the point of playing 3.Nc3 (before d2-d4) after 1.e4 c5 2.Nf3 d6? Compared to the “normal” 1.e4 c5 2.Nf3 d6 3.d4?</p>

<pre><code>[fen ""]

[Variant "Standard"]
[ECO "B50"]
[Opening "Sicilian Defense"]

1. e4 c5 2. Nf3 d6 3. Nc3 { Less common move } (3. d4 { Usual move })
</code></pre>
 19236: <p>Does it make sense though if white hates the sicilian 1. e4 c5 2. Nf3 d6 3. d4 cd 4. Nxd4 Nc6? Usually this move order leads to some Rauzer system after 5. Nc3 Nf6. 
The move order with 4... Nc6 gives White just the extra option to play some kind of Maroczy bind, and after 1. e4 c5 2. Nf3 d6 3. Nc3 Nf6 4. d4 cd4 5. Nc6 White ends up in the Rauzer anyway. 
I guess some people play 3. Nc3 against 2... d6 only, because they are playing it against 2... Nc6. After 1. e4 c5 2. Nf3 d6 3. Nc3, Black has no much additional options (except maybe 3... a6). 
After 1. e4 c5 2. Nf3 Nc6 3. Nc3 White manages to avoid the Sveshnikov, since there is no useful waiting move for black which still leads to Sveshnikov. </p>
 19250: <p>Najdorf players will have to go either 3. ...Nf6 or 3. ...a6. After the latter, White may make a move after which he deems ...a6 sligtly premature, such as 4. g3 (without saying that this will lead to an advantage for white over the Open Sicilian). I played 4. a4 once and got a good position after ... Nf6 5. e5 dxe5 6. Nxe5 Nbd7 7. Nc4 Nb6 8. a5 with a bind on the Q-side. 
After the former, there is 4. e5!? as well which is more dangerous than it looks and can easily throw an unprepared opponent off guard. The line is a specialty of 2700 player Mamedov.</p>
 18809: <p>If White is not willing to play a Maroczy formation (with c4), then Nc3 will eventually be played in almost any variation. Black has no clear way of preventing d2-d4 on the next move (3...e5 kind of sucks)</p>

<p>On the other hand, White may want to wait for Black's move before deciding whether to push d2-d4 or maybe go for a different variation against certain Black's responses (for example a closed Sicilian after 3...e6 4.g3</p>
 12873: <p>It basically just stalls for a move before 100% committing to the open Sicilian. For example, suppose you were playing White and hated facing this Sicilian (1.e4 c5 2. Nf3 d6 3.d4 cd 4.Nxd4 Nc6). You could use the move order you described and after 3.Nc3, only play 4.d4 if your opponent doesn't play 3...Nc6. If they do play 3...Nc6, then go for some Closed Sicilian.</p>

<p>Also in online bullet some people have done the 3.Nc3 move order against me because it takes half a second to realize what's happening and then play 3...Nf6 instead of 3...cd.</p>
