This hasn't been true for years.
They have realized that it doesn't matter whether you use Windows, Chrome OS, Android or Linux, or anything else: everything is in the cloud now, so the OS is pretty much irrelevant.
Azure, Office 365 and heck, even Linkedin are doing great:
https://www.theregister.co.uk/2018/07/19/microsoft_huge_2018...
So I very much doubt that Microsoft is sweating it about Chromebooks.