This doesn't explain Microsoft though, as that's probably a special case. They simply eliminated the Windows QA department, and instead let users do the QA. Why not? It's not like their users are going to switch OSes.
I don’t know about that specifically, but I’ve seen that as a common occurrence as a cost cutting measure in low risk situations. In that case, the risk is low because 1) it’s not safety critical and 2) the switching moat is large enough to ensure they don’t lose customers
