But Windows is where most people run Office, including all the back-end implications like Exchange and all the "Power" stuff.
It is a lot more than 10% of Microsoft revenue really (just not directly).
I agree though that they do not really care about the platform anymore. In fact, they care less and less every day about everything that is not AI on Azure.
Microsoft is working on separating all of the above from Windows without losing too much control but it is going to take a while.
Exchange should be SaaS for 99% of businesses. There's a web version of Excel that's probably OK-ish. I'm not sure what Active Directory looks like in a world without Windows.