Comment by dabbz
I personally point the blame on their constant breaking of SDK and API surfaces. From 7 to 8 and then to 10, so many APIs that were in use just broke and had no real 1:1 equivalent. I also think the death of Silverlight had a hand in it.
Not to mention that when they moved to SDK 8, you could only develop from a Windows 8 machine, that famously popular OS. So many unforced errors, many seeming to stem from denial that Microsoft does not possess the Apple Reality Distortion Field