I can see the use case for someone who wants a single OS install on the Steam Deck that does gaming just about as well as SteamOS does, but has a more fleshed out desktop experience (or even just a different one). The linked article goes into detail on various desktop-focused developments within Bazzite that wouldn’t really make sense for Valve to prioritize in SteamOS itself.
My Deck and Linux desktop regularly have shader cache updates every few days, but they’re generally tiny and finish near-instantly. I’ve never seen the behavior here of needing to download multiple gigabytes of shaders daily (and I’m thankful for it, with the frustrating data cap I have from my ISP).