this would be a great feature to have!! either a traditional keyboard shortcut, or a double-tap of a key infrequently used alone, similar to what activates Dictation (e.g., double-tap the command-key perhaps?)
Yes, why is it not possible to dismiss individual notifications on the fly with a simple keyboard shortcut? It's so annoying to have to put up with the popups, even for only a few seconds when I need to click on a tab there. I know I can drag right, but it would be so much faster and more convenient if I could just do it by keyboard.
And, no, I don't want to turn notifications off altogether. Every now and then there is a notification that I want to respond to and then it's great (incidentally, it'd be nice to have a simple keyboard command for that, too, but it's not as important as having one to dismiss), but the vast majority I look at real quickly and decide to ignore for now.