[com2kid]

> But wait, the instructions for this hypothetical platformer say you're supposed to be in a realistic environment, and clearly jumping that high isn't realistic, so I must be cheating... or maybe the jump button just needs more work.

This is why the speed running community separates glitch from glitchless runs.

Plenty of games have "game breaking" glitches, all the way up to arbitrary code execution (an example of ACE in Super Mario World https://www.youtube.com/watch?v=v_KsonqcMv0), and breaking the game into pieces is a different sort of fun than trying to play the game really well.