Wait, since when do they now require a KYC ? Haven't come across that information yet. Is it random ?
It's not random they require KYC to some users. The requirement existed years ago when they're still new and some of the reasons why they would ask it is mentioned on their terms and conditions.
They require it from users who have suspect activity on their account such as using a repeated ip from another account which triggers their system to questions the account ownership because they do not allow multiple accounts.
Also I would imagine they would ask those users who win a substantial amount of bitcoin or ethereum on their site for some form of identification before allowing them to withdraw their balance.