Evangelism in FOSS
One of the most dangerous things that can affect any FOSS community is the tendency of evangelism for the sake of evangelism. Promoting the Python stack, expanding the userbase, etc, should come only as a consequence of the content we produce as developers. If evangelism even remotely becomes one of your goals, your quality is sure to suffer. And it's not just the empirical evidence that prompts me to say this. It even makes logical sense. If we want to "promote" Python and related tech, our best market would be the young and unexperienced (and therefore non-opinionated) minds. But note that such audiences are also very fickle. They may not return for the next conference. And since they don't, we have to count on more fresh entries each year. And in the conference itself, since we're all acutely aware of the demographic, we spend too many talks pandering to this part of the audience.
Actually, I'll even go so far as to say that expanding the user base of a language is not the purpose of a PyCon. For that we've got activities going on all year. Come on! It's a three day event that happens once a year! If you're so concerned about evangelism, focus on the local chapter meetups. PyCon isn't the place to do it. It's a place for people to get together and exchange ideas. Teaching basics gets in the way of that like nothing else.
So, in short, focus on the quality. Users will follow.