From MY research:
From their Terms of Service:
KNOW YOUR CUSTOMER (KYC)
Stake reserves the right, at any time, to ask for any KYC documentation it deems necessary to determine the identity and location of a User. Stake reserves the right to restrict service and payment until identity is sufficiently determined.
Also if you happen to be from one of these countries, badluck:
JURISDICTIONS. Persons located in or residents of the United States, Czech Republic, Curaçao, Syria, Iran, North Korea or Australia (the Prohibited Jurisdictions) are not permitted make use of the Service.
What's funny is you trying to undermine Stake clearly for reasons which no one is aware of. The other posters have already mentioned that these terms are only invoked in rare cases for certain specific reasons.
You must be aware of this yet you still act like this rule applies to everyone who registers on Stake. I have personally been playing on Stake for months now without the need to ever provide my KYC details. Funny indeed.