What is the use cases that are enabled by sharing contact list when following? Query based upon "p" tag of kind 3, to get following count?

Why doesn't the following list belong at my relays and only there? So a follow and an unfollow, should publish this rather large event to the "targets" relays?

It becomes stale and invalid list as soon as I follow or unfollow someone else.

If I see a good reason to implement this, I'll add it to Nostria. Though it's an event that get's stale very quickly when distributed many places.