I think this is partly a byproduct of the non-chronological feed: the algo rewards quality (via visibility/engagement boosts), but it doesn't punish quantity, w

I think this is partly a byproduct of the non-chronological feed: the algo rewards quality (via visibility/engagement boosts), but it doesn't punish quantity, which incentivizes high-volume posting with no regard for your average signal:noise ratio. The resulting noise keeps users reliant on the algo for a coherent experience. When everyone sees a chrono feed by default, their own conduct is informed by the behavior they like/dislike in others. For example, I remember ~10 years ago when posting a picture of your lunch every day was widely understood to be poor form, precisely because it diluted everyone else's experience. It's a bit ironic that it's become a legitimate use case for instagram.