MS fought a legal battle with Dec over Cutler's move. Supposedly that ended up settled such that MS had license to Dec patents and explains why NT resembles VMS yet no lawsuit from Dec. Meanwhile other Unix vendors did not have said license. Fwiw I heard this story directly from Unix vendors OS devs when I worked at Netscape on servers (that supported IOCP on NT and hence often performed much better on a low end PC vs high end Unix iron).
The legal battle happened because it wasn't just that MS hired Cutler out of Digital - They effectively hired out a team that will as already working on design for next generation OS based on the same principles as VMS, and litigation went down on that IP.
Afaik Dec was pretty mismanaged at this time and Cutler didn't get his project greenlit. So "hired out" sounds more evil than it actually was. Microsoft saw the potential of Cutler's vision while Dec was busy being stupid. Why stay at Dec and work in something you don't believe in?
Oh, I didn't see "hired out" as evil. Whether it was mismanagement on Digital side to not greenlit Cutler's vision I'm not sure, but there could have been better ways even if they didn't want to replace VMS at the time.
https://techmonitor.ai/technology/dec_forced_microsoft_into_...