It's not actually hard to unfollow people on most platforms, though.
Twitter shows the Unfollow button when I hover over someone's name in my feed. It's one click to unfollow and I don't even have to leave the page to do it.
I think the real problem is a type of FOMO: People are afraid to remove any connections they've established, lest they miss something important.
Good point. That's why making it automated would be even better. Avoids the Larry David moment the author mentions.
Instead of fighting human psychology the apps should sidestep it. How about unsubscribing, but not unfriending? Shadow-unfollowing, settings like the Youtube bell for your content-stream?
I don't care to see your status-updates, but I want you in my friend list - there should be an option for that.
https://www.google.com/search?q=compulsive+hoarding&tbm=isch
But that, too, is something which a platform's UX design can influence to some degree.