I have an account for a long time now, because some groups, people and activities require it. But I've disabled notifications for a long time, and rarely log in except to check on events. I don't see a reason to deactivate it complete.

I have to say though, FB tries really hard to reactivate your notifications. It's especially annoying when it hooks into your mobile Chrome browser notifications (took me a while to figure that out!). And the fact it can't be uninstalled on Samsung devices - at least you don't have to login.