On September 29th, 2016, Speedrunners were able to beat Super Mario 64 with only a single key thanks to the discovery of Parallel Universes.
https://www.youtube.com/watch?v=j5j6l9ULxmI
[Grayda][1] was correct in theorizing that the first Bowser fight could be skipped using the "Parallel Universes" (PU) glitch described in his question.
If the name Parallel Universes makes it sound like this glitch is horribly complicated and difficult to understand.... that's because it is.