* Production appear to be the only QA they do
* Most of the time _something_ doesn't work... then you come back and it suddenly works, then it's broken again
* The news feed is non-deterministic. You can refresh and see something completely different
* Features [like the one in question] are always "opt-out" or "on by default". The attitude is "force the user to use the new feature" rather than improving it until people _actually want_ to use it
I'm glad to see them get into hot water on that last point. I see this user-hostile "we know better than you" authoritarian attitude taking over quite a few tech companies.