Before smartphones (generally speaking), the majority of your notifications were on your computer. If you walked away from it, you were no longer getting them.
Today, you've got a notification blaster in your pocket/purse, which is bad enough for work stuff, but if you participate in social media, it's a FOMO machine too. By default, all of your notifications are artificially urgent.
I'm a little older than the average HN'er, so my attitude in life has been closing my social circles to be a very small group of people with richer interactions, as opposed to enlarging it to a large group with less rich interactions. Because of that, it's been pretty easy to wean myself off of FB (not that it was ever a big part of my life in the first place), and I've never considered Twitter, Instagram or anything else to be that interesting. I will admit that I enjoy Reddit - those cute animal gifs are quite relaxing after a stressful day, but I don't use Reddit the way most people use FB or other social media.
When it comes to notifications, I turn a lot of them off. I keep my work notifications on during the hours I consider myself available (for urgent stuff, people know they have to call me), and tightly restrict other notifications that can be distracting.