I think you are underestimating the breadth of the Steam library, the sheer API surface (documented and undocumented) available to decades of proprietary Windows games and their respective DRM and anti-cheat solutions, and the depth of the technical issues which will present themselves when trying to get all of it to run flawlessly. I'll say it right now: that's not happening.
I'm more than willing to eat crow if they actually manage to do it (and e.g. PSO2, which is an MMO with a decade of patchworked technology and a semi-custom anti-cheat behind it works at launch), but Valve implying full Steam library compatibility is the biggest (basically only?) mistake with how they've presented the Deck so far IMHO.
I don't disagree at all. In fact I have said multiple times that the idea of the entire Steam library being playable seems like a miracle to me. However, Valve has stated that as a goal so many times now that I believe them. I believe they wouldn't have said that if they didn't think they can make it happen. At the very least I expect them to have all the popular games up and running for launch and patch in support for any outliers. I don't think anyone would care if a random asset flip didn't work.
IT'S HAPPENING....
New EAC in Back4Blood works in Linux
Boy is it a relief seeing you here! Welcome!