There are, the issue is they are hard to find, I'm with you.
The most popular onlyfans accounts are a sad state, mainly because I'm guessing gays are fast and loose with their money for people who frequent the gym.
I've seen the content of some popular accounts that were hyped to high heaven that were just a bunch of pitiful 30 second solos and flexing. There are exceptions like Griffin Barrows etc but on the whole its a very muscley white space, some not even being gay or having sex.
I'd love to discover more myself, you just kind of have to dive into twitters that you find interesting and hope that someone youre into posts often to be worth the price and that they can find people to make content with, (some with body types I'm into have told stories of how others have not responded to requests to make content because of their body, race etc) Ive seen some promising looking Brazilian accounts clips on twitter.
I'd blame the content creators but if people will pay you 10 dollars a month for you to continue to go to the gym for a 10 second flash every few days, why wouldn't you? it seems to actually be working.