The thing is a lot people have this misconception that "No Kyc" means a lifetime pass when it actually means "No Kyc at registration". Most of these gambling sites have security software running in the background at all time so when you try to engage in anything that it's strange to them, they automatically ask that you provide your ID, sometimes, you're required to do so even in small transactions.
I do not think it is a misconception but it is more about different point of view when it comes to a term "NoKYC".
In general understanding, NoKYC should be No at all means that KYC wont be asked lifetime.
However, in marketing point of view, NoKYC is only a marketing gimmick to attract players who cares about privacy.
Basically it is reasonable if people expect no kyc at all once a casino claim themselves to be a NoKYC casino but from the casino side, they will still have the right to ask KYC at anytime.