> If I get notices from pages/groups I dont care about anymore, I either unfollow or mute the next time their post annoys me.
I do that as well, but I think it's extremely rare among Facebook users. Everyone else I know either:
* Puts up grudgingly with "spam" they no longer want to see, or eventually
* Complains "Facebook is full of crap these days, I'm deleting my account".
A filter algorithm is a much better experience than manual unsubscribe for most users. With how easy it is to "like" anything you see on Facebook and the rest of the web, it is almost necessary to assume that subscriptions should "expire" unless the user keeps actively interacting with the page.