Considering Reddit and 4Chan are things, Wikipedia is far from being the most toxic .
Maybe the most elitist
Maybe the most elitist
On the other hand, I find a community like Stack Overflow to be much worse because the BS can strike any time, any place. Between questions marked "Off-Topic", and snarky replies, and the non-replies ("We won't answer your simple question because you should not be asking that!") you can't avoid the negativity.
The only winning move is not to play.
In subreddits which are non political you'd still see people injecting nastiness.