This is a never ending discussion in many topics. I wouldn’t say that KYC is always useless as in some cases I can get why casinos want to check it (especially if you want to withdraw a big amount). But a lot of casinos are trending to asking KYC so we just need to adapt and live it.
Well, there will be a never ending discussion and argument about KYC because people have different view about it. One side understand the need for KYC while the other side wanted to tell the importance of privacy. For my part, I always think that casino implement KYC because it is needed to have a smooth business transaction since the authority requires it and the casino being a business needs to comply.
KYC has also had its good side like in times when a person's account is hacked, accidentally deleted his 2fa authentication apps, and any instances that the account experiences a problem and needs proof of ownership.