Floating rings
Every platformer does it. Mario, Sonic, even earthworm jim. Jumping through these floating hoops. Oh and Superman that one time, Almost makes you ask "in this weird cartoon world, why are there floating rings everywhere?" I can accept thousands of henchmen being dispatched by a plump italian by a jump, but where do these floating rings come from?
Seriously, though
I'm not actually asking about why those rings are physically there, (that would be insane #gametheory) but why do video game developers use them as level obstacles? So you can argue that they're there just because they're really easy to add a quick challenge. That would only explain why they were in early games (or apps) which were cheaply made and usually made in a hurry, but what about the big triple A games that still use them. They may not be floating but they're still there: checkpoints.
For the most part they're there as a patchwork job to help the player get through the level when the design isn't good enough.
For the most part they're there as a patchwork job to help the player get through the level when the design isn't good enough.