Getting back into a chat is harder the longer you've been away.

The longer you've been away, the more the notifications backlog piles up.

There were 30 unread notifications, so you waited to dip back in.

Then there were 300, and it was even more intimidating.

Now there are 3000, and you'll never look again.

This is convex: self-accelerating as you get out of balance.

Infinite feeds do away with this by saying "you can never be caught up, don't worry about it."

A chat implies every message is important.

A feed implies that any item is skippable.

The feed is the only UX for serendipity.