I think some casinos don't care about email, kyc and so on, they limit users because the casino detects that the user is doing multi-accounts, they track from the IP of the user itself.
IP is unavoidable, sometimes some users who gamble use different browsers, Chrome to register at the same casino, multiple betting destinations, with different accounts, maybe some casinos don't care about that if the user loses, if you win a big bet, problems arise, blocks, limits and so on, I think that's a problem we often see here.