Because they can sell Microsoft tablets and phones.
Microsoft was taken to court by Apple/Macintosh years ago for infringement. Microsoft’s saving grace was they said they are only selling software, Windows is an operating system not a computer. So, Microsoft is a software company not a computer company. Notice they didn’t say “Not a hardware company”. A tablet technically isn’t a computer.
So if Microsoft can get you to enjoy their operating system on your pc. Then they have a chance of creating their own “Computer Tablet” and calling it a windows computer.
Now if Microsoft can get rid of the typo issue of touch screen keyboards, and somehow reinventing the scroll wheel function of a mouse on a touch screen monitor, then they have a fighting chance. The main issue is the design software most power users use would be murder on a touch screen without a scroll wheel and a the third button function of a scroll wheel on a mouse.
So if it comes down to the only way to Microsoft is through a tablet, some of us would have to step down and install linux with WINE so we can still use my programs that currently only work with Windows. Autocad, Magix Music, Etc.