On my PC and my phone there are ample opportunities for notifications. Some of them are system notification like charge levels, but most of them come via applications. One could get a notification for every email, every instant message. Browsers can now relay notifications from websites to the user. On the phone you have messages, calls, reminders.
There are the maker and manager schedules. In short a manager works on a rather short time scale and does a lot of little decisions. The maker in contrast goes into the zone and works on a problem with deep concentration. Ripping the maker out of that concentration will result in a loss of a lot of time because they have to get back into the zone again. Notifications are interruptions that are easily turned off.