I think Steam Decks wouldn't ever have existed without Linux enthusiasts as early adopters of Steam Decks and the few previous iterations of Steam + Linux either playing games on their own machines or on the previous iteration of a Steam Linux computer. If at any point it was all tied up with DRM and that complete loss of control required for anti-cheat it would have just died and not be seen again.

The only way it changes course is an enormous rug pull that removes most of the differentiation between PC and Console gaming and you end up with Steam as a dying product unable to compete with either other modes of PC gaming or the dominant console players. (Sadly that's basically what I expect when gaben retires)