Well anon. Let me break down why F/F breaks /co/'s mind
1. Korra induced PTSD (even though /co/ shilled for Korrasami before it happened)
2. Heavy post-2016 election /pol/Reddit colonisation.
3. Large gay male and fujoshit presence.
4. 4chan Contrarianism.
5. Self-insert fags.
6. Shitposters who end up getting lost in character.
/co/ is full of trannies, fags and cucks.
But the real reason is some weird kind of complex that started when the worst boards started to call them the 'Tumblr' of 4chin, some of the worst crossboarders, mostly from /tv/ that came in the middle of le ebin Marvel vs DC console war took it too seriously and went out of their way to disprove that by making /co/ some kind of mutant rapechild of /tv/, /v/ and /pol/.. which i guess at that time it was called /news/?
Anyways it just got worse when Korra ended and keeps getting worse because /co/ now is by default set on hating gayness, female gayness in particular, and they keep getting btfo by the comic and cartoon medium just getting more blatant about using non-straight chars from time to time.