One unfortunate aspect of this phenomena is that as reddit "evaporatively cools" (ala https://www.lesswrong.com/posts/ZQG9cwKbct2LtmL3p/evaporativ... ) as the more level headed people leave reddit gets even more radical.

It's even possible the places that people then move to (such as HN) also get more radical if the leavers have higher levels of radicalism than the place they join.