Windows 10 replaced 7 for most people because 8 was a piece of junk. Windows 7 was old by the time 10 came out so there was pent up demand and 10 was a pretty solid showing.

There’s not much that’s compelling about 11 and they’ve introduced unwanted things. It shouldn’t be surprising that people prefer to stay on 10, which is one of the better operating systems Microsoft has ever released. Combine that with the dominance of Linux in the server space and what seems like increased adoption on the desktop and it’s a recipe for poor numbers. For a lot of developers, it’s easier being on a Linux desktop when Linux is the deployment target.