Eh, WSL is still enough like Linux that it could be the best option for a lot of people. No risk to the computer being unable to boot whilst still giving you the ability to play with Linux tooling.
And credit where credit’s due: Microsoft details how to do a bare metal install, which is the most likely option to wipe Windows from your machine in the first place.
This doesn’t affect valve at all though. It’s borrowing their tech that they’ve made open source, and figuring out how to use it elsewhere outside of steam.
Actually, it’ll benefit them. More eyes are on proton and any fix will benefit everyone, including games played via steam.