I was using Linux before there was a Steam, and I’m still here. You speak as if the “default state of being” is being on Windows.
Disregarding that, why would a single launcher/client/whatever dictate what OS I use? What I enjoy while using steam is not the openness of steam, what I enjoy is the freedom of choice on my home turf. I enjoy living in an age where I can boot up my trusty Linux rig, finish my work, and contemplate three or four launchers before picking one and facing choice paralysis while picking from hundreds of games (yes I’m very excessive and haven’t even finished 0.01% of them) that actually run like a charm.
This is a reality I love and celebrate. This is the year of the Linux desktop for me.
I don’t love the Steam store, but I love Valve, because they made all of this possible. Even if all of the above is incidental in their pursuit to build their steamdeck. At least they did it the right way by contributing back upstream to the FOSS community at large.