As a long time Windows user, I get the feeling that Microsoft considers Solitaire and Minesweeper as the key differentiators on their platform. You use Windows to have Solitaire and Minesweeper; not for stability, developer APIs, backwards compatibility, security, etc. Those are all add-ons from the zero-interest-rate days that nobody cares about. Windows is about throwaway games; that's why you buy it instead of a Mac which comes with NO GAMES out of the box.
As a result, this is what every PM wants to rally behind. "Increased revenue on Minesweeper by 4000% QoQ." That is how you become the CEO of Microsoft, probably! So you gotta do it.
Having said that, I have neither Minesweeper nor Solitaire on my Windows 10 Pro install... so... I guess I'm technically incorrect. I do get this feeling that those two games are really what Microsoft sees the PC experience as being. Nobody ever told them that both games are actually super boring, and people only played them because the Internet didn't exist back then and it was better than staring into space while your typewriter warmed up or whatever people did in offices back in the day.