Microsoft got to burn those kinds of resources on the compatibility problem due to having had a near-monopoly on the desktop back in those days.
That isn't going to be repeatable for pretty much any other software company other than a FAANG, and certainly not of open source projects, not even Linux. People don't pay enough to open source for that kind of support.
It is true for the kernel though. Linus has a strict non regression (of the user code) rule. If some user code starts to break because of a kernel change, the kernel team takes the blame no question asked.
