The majority of my fandoms have been huge slash fandoms, and AYRT is right. The majority of people have a preferred headcanon one way or the other but are not adamant that their preference is The Right One.

There's almost always a vocal minority that go overboard and practically crusade for their OTP. There's also almost always a vocal minority that feel they need to explain to everyone why it's stupid and irrational and annoying to ship X and Y together. But those factions truly are the minority, even in the fandoms that seem the most batshit from the outside.