If their skill is to create popular videos, they did not had much choice. It is not like there would be other popular video services that would compete.
Is this really true? I mean, there are hundreds of video hosting sites, is YT really the only way of making any money?
This is like saying that the only way to make your business sustainable is to get a reserved place on NY Times Square... are you really entitled to it?
Typical users aren't relevant here. We're talking about Patreon supporters, people who gave money to a single creator and want an ad free video. They can click a link to vimeo.
But they need to know first. Who looks for something new on viemo? Sure if someone points you to them you will look, but do you go there just to see if there is anything interesting when you are bored?
For many of them, it is youtube or nothing.