exactly, it's just a marketing gimmick. to me, if you say you are KYC free, that should mean you don't enforce KYC ever. and as you said, every reputable casino has the same KYC terms, but they don't advertise themselves as KYC free.
Ever is where they draw the line. Let’s not forget, it ain’t just a service but, a business. It’s important that they stay legal where ever they operate and put of those terms is that, they comply with the jurisdiction of where they function. Now, KYC becomes a needed document as a way to combat money laundering. When a casino or bookie becomes big enough, they seem to enforce this mostly because they are pressured by jurisdiction. It becomes some serious identifier for fishy situations from certain gamblers.
Maybe it is a marketing strategy but, when the strategy isn’t good enough no more or when it doesn’t appeal to gamblers, they could always leave for a better alternative.