I don't think it's sentimentality, exactly. Who picks Azure or OneDrive or AD or Office 365 or Sharepoint or Teams or any Microsoft product or service if they're not already running Windows? The desktop operating system, "legacy" though it may be, has near universal reach and has therefore been key in pushing people to their more lucrative services. But they pushed too hard, it's too obviously shit, and now people and enterprises are looking for an exit. What then?