The word "extraordinary" has some overblown connotations here. This is the only visa for artists (and it's not even an immigrant visa), and all you need is a track record of success. Which puts you above an ordinary artist, so yes, that's the definition of extraordinary. But the colloquial meaning of the word suggests it's meant to be reserved for some elite 1% of creatives which isn't true.
I think we should spend less time looking down on onlyfans artists. They do good work too, some of them. And like the article says you really have to be exceptional to make money with it.
If you read the paperwork for the visa application, this is pretty much all it's about. no one is trying to judge the quality of your artistic contribution. its all about how much money you're moving as a professional artist.