[InclinedPlane]

Windows has greatly improved in this regard but it's still a huge pain point. I believe that the frequency of required reboots after patches is likely a leading cause for machines remaining unpatched.

Ultimately it comes down to lack of having "no reboots" as a clear goal. SQL Server has a pretty strong goal of being able to patch a running server without rebooting and they do a good job meeting that goal. For Windows OS it comes down to programmer laziness winning over in the absence of a directive to avoid reboots.