Isn't that sort of contradictory? The rest of the UX is so great that people want to use it despite the crashing.

That's when you know you're peddling a powerful drug, eh product I mean. & simply right there that's Facebook's moat. I don't use FB, but gotta give to them anywhere I peek at someone's smartphone in public spaces, they're using a FB product e.g FB, Whatsapp or Instagram. Hell, right now FB pays my rent, cause of the tools I make at work that integrate with FB