I don’t quite understand the criticism. It’s not gonna be top of the line, but it’s more than enough to replace my dying laptop from 2015 that I pretty much only ever use like a desktop anyway. And I can save myself the time and effort of picking parts, building, and dealing with shit not working as expected.
If someone is looking for an all-in-one device, it is a valid criticism to point out.
As it stands now SteamOS can’t play the big flavour of the week multiplayer games. If that really matters to you and you don’t have somewhere else to play them, a steam machine isn’t for you.
I dual boot for this reason but default to Linux for everything that works there.