Thats great for you and others should give this a try. However, its unfortunate that if everyone did do this facebook would simply force an undo of that action...removing the unfollow feature and subscribing everyone again or whatever it may be.
Facebook wants you engaged; they don't give a shit what you're engaged with. If me chuckling about a derpy kitten lets them throw ads at my eyeballs, they're all for it.
I did much the same. I unfollowed every page, and any person I hadn't seen in person within the past year.
My Facebook is now a carefully curated list of people I like, and cat pictures. It's done wonders for my mental health.