Unintended side effects of the PS4 3.00 update.
The PlayStation 4 3.00 update brought with it a lot of new social features, such as communities, and the ability to make Favorite Groups. Favorite Groups is an excellent way to organize and keep track of your friends, and to interact only with the ones you want to at a given time.
It is also something you absolutely should not be using.
The issue is that once you are added to a Favorite Group, you are bombarded with all manner of notifications- every time someone posts a message, every time a change is made to the group, every time there is any interaction within it. Everyone in the group will be spammed with notifications, probably detracting from their game, and honestly, they might just end up removing you.
On second thoughts, this may be an excellent tool to trim down your friends list, and not come out as the bad guy who removed someone else. Thanks Sony!