Citation?
I got a lot of crap notifications for years and years and have completely abandoned FB at this point b/c of the low signal to noise.
>rather than our usual operating model of sending all relevant notifications (either rated 4 or 5 on a scale of 1–5)
Just because something is "relevant" to me doesn't mean I want to be notified. Usually I don't.
I go out of my way to have zero unread notifications in any software I actively use, even if it means making liberal use of Mark All As Read. This lets me visually scan for where activity is without visual noise.
By definition a relevant notification is something you want to get a notification for.
What might be "relevant" to most people will not be relevant to me.