I haven't really ever used it. I used to buy everything Blizzard made (OK that's an exaggeration, but I was all about WarCraft/StarCraft/Diablo...). Before Steam, I bought lots of games on disk. Now I buy most things on Steam. And I haven't bought anything Blizzard since Diablo III.
Why wouldn't Steam continue to be competitive against Game Pass?
(I'm just one person, but among the people I know that play PC games, I don't hear about Game Pass much. One person mentioned he's on a 14 day $1 trial - that was the extent of it.)