> That's the reason you see websites requiring phone number or credit card verification these days

And this is trivial to overcome (depending on how eager the registrants are). The pro freeloaders have access to many different numbers and typically order SIM cards in bulk, and CC's can be spun up easily too all using different names. The real pros buy these in bulk from the dark web, so it's a non-issue for them. Passport scans and a 3D selfie that matches is the gold standard for auth now.