Re:Apache Foundation disallows use of the Facebook “BSD+Pate...
by nojvek on Tuesday July 18, 2017 @12:31AM
(#14794269)
You'd be actually surprised how many teams inside Microsoft wrote their own smaller versions of OS libraries. It happened a lot less after Nadella era, but Ballmer era had a "we can't use anything not built here"
Also see this HN thread from a year ago: https://news.ycombinator.com/item?id=12108273