Dota 2 community may not be the most friendly bounch around, but believe me, the current Dota 2 playerbase have it easy.

If someone ragequit, feed or call peoples name, there are several ways to punish him, many automated. Bad experience with players happens, but they are rare enough to stuck out.

On Dota 1, most games were like that. It was basically part of the experience, and while there were some ways to at least diminish the problem like custom blacklists, it was far from perfect.

And as far I know, there was no punishement for being an offensive prick. On the good side, there was no voice chat so you at least won't hear him screaming on the mic.

Overall, the current Dota 2 is the best Dota 2 experience one can have, and I think lots of people will be frustated by custom games when they meet the raw, original, unbridged Dota experience where you are not punished for leaving.