Microsoft are deep into the government with exchange and Active Directory with most being migrated to Microsoft365 and Azure.
Add in MS Teams, SharePoint, MS SQL, 30 years of business rules living in old excel macros that ends up running the entire company.
Windows enterprise licences would be a tiny part of their spend and far too costly to mitigate away from. Most large corporations are virtualising old windows version just to keep their existing legacy apps runnings.
Good guy GOG wants you to actually own your own games, forever.