considering the millions of hardware/software configuration combinations to be dealt with, i can't see how you can safely say that an update won't be 100% reliable.
just like any update.
damned if they do, damned if they don't. if they don't provide updates, people complain.
if they do and affect a subset (and it is normally only a very small subset) of users, people complain.
linux and mac updates cause issues too... microsoft are just an easy target...