Everybody here is debating whether Valve is trying to crush windows.
I took it more to mean that Valve realizes that Windows is the dominant PC OS and so they're trying not to appear as if their goal is to crush Windows, on account of how if that's their goal Microsoft could just make Steam inaccessable on Windows.
Now you could argue that there will be a patch, and a hack and blah blah blah the average user ain't got time fo none-a-dat!
User installs steam. Windows blocks installation. 70% of users just give up. "Oh, I guess this only runs on steamdeck. Oh well."
And just like that Valve loses 100% of potential purchases from that average windows user who hasn't even done so much to their system as changing the theme.