> So fb and Twitter are either built by incompetent devs or they have too high a mgmt interference? (Since they auto play videos)

That seems like it's asked with the expectation that the obvious answer is "no", but I believe it's "yes". Well, I have no idea of the quality of their devs, but someone in the decision chain thought that auto-playing videos was a good idea, and he, she, or they were wrong.