It's not a scam but of course It can be questioned....
Most of casinos have in place a forced KYC in any case for all players involved. Even if this is not really clear from their webpage, there is always some comments (even vague) in their ToS.
In the past, with a casino, I had the chance to analyze one of these scam accusation. I would say... not all are real complaints. Most of the times gamblers know very well that they are gambling without following rules or just making multiple accounts - value bets and so on.