Pretty sure that content is not what is bringing in the monies.

I watch several channels on YT, and I think they have excellent value (educational like 3Blue1Brown, entertaining like Davie504, musical like Ichika Nito and so on). I really enjoy watching/listening to them especially when I do something around the house like cleaning. But the moment they said they go OnlyFans and I have to pay $10 in order to watch them, I can't imagine I'd switch.

Is it OnlyFans or paying money for things that's the issue? Would you pay $10 on Paetreon or for YouTube premium? Would you pay $1 to OnlyFans? How about paying $10, but no one would know you were paying OnlyFans?

It's the immense hassle involved with paying small amounts of money to many different people. Sites like YouTube (and presumably OnlyFans) fix that problem.

Why not just feature that stuff on the homepage? Most adult-oriented channels are run solo, so they're distributing links via social channels.

Same as Twitter. It's awash in porn but you wouldn't really know it if you stuck to the default trends and searches.

There's benign stuff on PornHub too, but I don't think they'd be able to survive without their adult content either.

Yes but if somebody says "drop your OF" is not talking about gardening. Mostly it is known for sexual material.

InRange moved to pornhub when they were banned from Youtube. While cute and all, that made 0% revenue for them.