I don't mind the idea of notifications when I have a web page open in a tab. Like, sure if I receive a message while I'm looking at another tab, let me know!

But I was a bit shocked to discover that I was getting notifications from sites that I did not have open, then I realized that when I register for notifications the browser will continuously poll that site in the background, no matter whether I've browsed to that site in this session or not. That was when I decided I didn't want any notifications.

It's not even the interruption, but more the knowledge that my computer is casually making HTTP requests in the background, continuously, on a site I haven't even browsed to, that I don't feel comfortable with..