The idea is that any place that isn't explicitly right wing will eventually become Left. It doesn't mean that those explicit right wing places aren't capable of becoming the same echo chamber, mind virus filled places as a Leftist one. Arguably they are more susceptible to it, because they literally cannot leave as there are vanishingly few places they can even be openly right wing.

Anyone who had a slightly unpopular on T_D can vouch for how little different they were from basic subs in terms of all the same echo, dogpile etc. problems.