I think generally the 6s community is bad at articulating itself to casual players because most of the really insane conspiracy-esque takes about how "big comp" is ruining tf2 are borne out multiple cases of complete misunderstanding building on top of each other.
I do think the easiest way to fix this is just more competitive players talking about competitive tf2 because on the face of it, if you know what you're talking about then it's really simple to explain that this class limit is this way because of x, or this is a strategy that players will do because of y
In my own comments section i see a ton of pub babble or people who are belligerent at the mere idea of any restrictions being put in place to begin with, but I also see a fair share of people who have had their minds changed, want to try playing 6s, or just appreciated the new perspective on things without expressing interest in playing
Also,
Rahmedoften making casual players look more toxic than the game's comp community which is rare
From what i understand from other games this isn't that rare at all, and often times casual players feel threatened when people talk about game & strategy optimization as though its being imposed on them when it absolutely isn't