Mass adoption of crypto will come with the same problem - middlemen slipping in under the guise of efficiency and convenience, who will then be compelled to cooperate with big brother.

The big difference is that those middlemen won't be required for payments to function so OnlyFans could ignore them and take payments directly.

PayPal and other pseudo currencies already did, for a while. You bought virtual currency (which PayPal was at first, and so was e-gold, webmoney, etc) and traded that for anything you could.

Then PayPal wanted to go big, other virtual currencies were caught in fraud scandals of their own (not their users'), people just lost trust and interest when card processing became more common.

Some are still around but sellers can't be arsed to use them. Maybe they will, once again.

What type of fraud? It seems to me that it would make it basically impossible to defraud a merchant with a stolen payment method (much like cash). Do you mean merchants defrauding their customers?

Right, but that means it will be a lot easier to scam regular people. The ability to clawback money is a vital way of stopping scams over the internet.

As a customer I wish I could have the option (in return for a cut of the interchange + fraud fees the merchants pay).

With ~90% of it currently being used for speculation or illegal activity, I don't see it getting real traction.

You're assuming the government won't just ban it entirely.