Also, did everyone just forget that Valve already tried this before? The people who buy prebuilt PCs do not want Linux and the people who want Linux do not want prebuilt PCs.
I actually don't think that's an apt comparison for this. Valve isn't inventing the wheel here, there are dozens if not hundreds of companies that sell prebuilt PCs. I'm a massive fan of Valve and Gaben by the way, I just don't think this is a solid business decision on any front.
It's not a pre built PC, it's a gaming console that can also be a PC, if needed. That's how the steam deck is marketed, that's how the previous steamos PC was marketed, and clearly Lenovo thinks the marketing will work. A unified simple introduction to PC gaming as cheap as any console but with near infinite backwards compatibility is a pretty good sell to the normies who have nothing but marginal upgrades to look forward to in the console space.