Indeed, KYC is a requirement that is applied by casino sites for each user, especially for users who will make withdrawal transactions with relatively large amounts.
However, as gamblers, we shouldn't need to feel disturbed and be concerned about the obligation of every user to do KYC.
Because the existence of KYC requested by the casino site has a good purpose in terms of security from the casino site and security for every account registered on the site.
Passing KYC is the requirement of regulator. Also in many countries casinos must inform the tax inspections about big winnings. Nobody wants to pay taxes.
Also users must be sure that their personal data are kept in a safe place and nobody have access to them.