I believe any person have a Facebook account, it means almost people's identity already leaked in the first place.
Having a Facebook account and verifying KYC on a platform aren't the same. Facebook doesn't verify your identity in the first place. Facebook won't know if you are using fake information to create an account. But, Once you create an account on a casino and you have to submit KYC. You cannot submit fake information to verify your account. On top of that, You cannot compare a Facebook account with a KYC. Nobody on the internet knows if the account is real or not.
Learn Bitcoin you got it wrong there because to have a verified Facebook account all you documents must be verified and what Plaguedeath was trying to say is that identity leaking is possible and we are vulnerable to that and as a result lot of crimes have been committed, but also we must know that there are levels to KYC.