To be fair despite Valve's tech stack being easy to replicate, their actual competition mostly hasn't replicated their feature set in full? Epic took a while to ramp up to "shopping carts" despite having a pretty large funding model, still doesn't have little gimmicks like trading cards and chat stickers, w/e. That's not really moat but it seems like the competition doesn't want to invest to exact parity.

(And a lot of stores like Ubisofts or EA's were very feature lite tbh.)