Sometimes I try to swipe up and the phone interprets it as a sideways swipe and dismisses something I hadn't read. So I've hit the history feature to see what that might have been.

Now, what I'd prefer is an undo button, and I wouldn't have expected that history to persist more than 10 minutes, but it's not 100% useless.

Dunst has one by default. I have used it twice. Once when I was very tired and couldn't output something into a file for some reason (I think it was a full disk) and piped it into a notification instead and once when a program put some error message in there and the notification expired before I read it.

It can also be fun for seeing how your perception of notifications compares to the ones that actually show up. It is however important to remember that it exists and to not let important data end up there.

If you accidentally dismiss a notification, you can go back in the history to see it. Or if you dismiss a message notification that you want to respond to later. Or if a notification keeps popping up and disappearing and you want to investigate.

Because it's extremely useful? I had a shitfit when I bought an iPhone and then realized if I accidentally dismissed a message it was just erased from existence.