Comment 12 for bug 334809

That's true that if a program is sending too many notifications, it's the program's fault. However it makes sense to prevent this kind of things to happen because the notifications are system wide and there are bugs.
I think that a notification system is quite different from a window manager. In fact your bug examples happen inside the bugged application while the notification are handled externally.
What do you do with an app that opens 200 windows? kill -9 ...
What do you do with an app that has sent 200 messages? Even if you kill it they'll be displayed, so the only solution is to kill Notify OSD.
That's the reason because there must be some kind of control about how apps use Notify OSD.