Mandatory KYC is imposed by the government which can't be in the hands of gambling sites but sometimes site is also using this KYC as a weapon to stop paying the huge rewards in case if the Gambler violated terms or can't able to verify the real identity for some reasons.
And that made Gambling site powerless against obligatory because even if they wanna sustain the promises to their players but their hands are tight from the Government policies .
i may not blame casinos then even how irritating changes from the recent rules but of course if you don't want KYC then play in real casino and not in Online sites.
Now the policy has government intervention because they also want to be legal in the casino, especially in the license, therefore inevitably KYC obligations must be implemented in casinos and have started to apply in several other casinos.
Remember that not all casinos have to be KYC, there are also those who are still anonymous for users and casinos are still providing this and I think that in the future not all casinos will be KYC, now I still feel pretty calm.