If someone buys the game om xbox, microsoft gets a direct 30% cut. If someone buys it "on windows", not so much. That is a very distinct difference.

Yeah it's microsoft's operating system, and they do sell licences for it, but I very much doubt anyone is buying a windows licence just to play the game.

Could they have done more than skip the smallest console by install base? Sure. Is it performative? Maybe. But it sends out a clear message regardless, a message I am in favour of.