>>724109392 (OP)
Steam OS can be run on desktop just not on most hardware and not an official release. Also it won't matter unless people are using it. It's not enough that nerds install it as an alternate OS on PC and normies don't but it in a store. So valve is better off releasing more reference hardware with steam OS on it like the steam deck. Deckard/Frame is next for VR. Then Fremont for a living room PC/console. Also valve will probably never sell hundreds of millions of units of these things, third party partners need to step in and produce hardware with steamOS installed.
Also valve doesn't "make the OS". SteamOS is a valve distribution of arch linux. The good thing is if they can make SteamOS popular enough it will defragment the linux community and work will be focused on arch and get pushed downstream to SteamOS.