What's really baffling is that iOS hides older notifications after some amount of time, or screen unlockings, or something. I like to leave notifications around so I can remember to handle them later when I unlock my phone ("oh yeah, I need to read/respond to that email"). Instead iOS just removes them from my lock screen so I don't see them when unlocking and I forget they exist. They're still there--you can swipe up from the bottom to bring back your hidden notifications--but that requires you to remember they're there, which is the whole reason I didn't dismiss them in the first place.

iOS's notification system is shockingly bad. Android is leagues ahead here, both in features & configurability.