Steam decided to kick all blockchain games because they tend to feature real money trading for in-game items.
IMO this is a good decision, at the current state blockchain games are just another vehicle for speculative investments and even scams, and unsuspecting people shouldn't be lured into them.
And I can't agree that blockchain is the future for gaming, I'm a gamer myself and I never thought "Oh how I fish this game was running on blockchain". I never had any problems with centralized game servers, so why fix what is not broken? Especially since it's the blockchain that has problem like high fees, bugs in smart contracts, confirmation times. Not to mention that introducing real money into games tends to leading into very poor ecosystem.
So for me, it's really a good decision from steam.