Normies don't want to suffer through a windows PC update when they're in the middle of a kill streak, and we know how Indian infested Microsoft is; an avalanche of errors is inevitable.
Normies also don't tend to go with PC's for gaming because it takes a little bit of know-how in how to set it up and get going, even if it's a prebuilt. Microsoft's worry with the Steam Machine isn't Windows 11 being shit, and it's not like it's gotten so shit it's
literally unusable, that's all people exaggerating shit to have a reason to complain. PC's will still have Windows users, and Windows users will use Steam, so both Microsoft and Valve will be happy, little difference there. The one in ten thousand PC gamers that'll switch to Linux won't matter to Microsoft since Windows isn't just a gaming OS contrary to popular belief, all the corporate users and preinstalled instances on laptops will chug along just fine. Ideally everyone would take this distinction and memorize it before running their mouth about how Valve will destroy Windows to not sound like mouthbreathing mongoloids, that's not what Valve is competing against and was never planning to, SteamOS is just a side effect of Valve realizing their entire business is tied to Microsoft via Windows, not Valve declaring war against Microsoft.
The real turmoil for Microsoft is the entire Xbox division that doesn't know what the fuck they're doing at this point. That's where Steam Machine can actually fuck Microsoft over. Xbox consoles aren't selling, and yet they keep bumping their prices up. They're planning to ditch consoles altogether. The fucking PS5 is selling better than Xbox consoles. And now Valve is coming out with something that can play the vast majority of Windows games (as long as you're not a competishit player, and those are in the hundreds of millions and all using Windows but at the same time they don't play on consoles so not really a concern here) without much hassle since the Steam Machine will act as a launchpad for Steam Big Picture and that's a solid console-like experience. You'll be able to sit your ass down, grab a controller and play. And Microsoft won't see a penny out of this, the "console" will be Valve's and so will be the game store.
The Xbox division is already circling the drain and constantly shooting themselves in the foot, and now Valve is basically threatening their business hard. Then again, it's so pathetic that there's not much to compete against. Chances are the GabeCube will eat Xbox alive but will still be second place to the PlayStation, as that still remains a genuine console worth a shit when you're looking for something to buy and play.