Maybe youre right about them pursuing engagement for its own sake, maybe they're not in that game.

Though, whatever approach you have in discovery, or ranking posts, you're having an impact on your users, and promote a certain dynamic, no? I imagine their next approach won't be the equivalent of letting go of the steering wheel, just maybe not mindlessly chasing the same metrics as they are currently.

Maybe that's a little too social psych to call tech/engineering, but I imagine the data science that would support that would be quite exciting.