It kinda became a must-know trick for translation, but you could hit angles just right and "skate" on them, gaining velocity the whole time. A quick look got me this far: youtu.be/d846EASxiEk?... It was a trick any hardcore learned.

Yup, that's one of the earlier versions of sliding. You had to time your jump input almost frame perfect, right? Before that we had bunny hopping in quake, especially after a rocket boost, where consistently jumping the same frame you land let you maintain higher than max move speed.

Yeah seems like that was a bug embraced by the community that kind of got "tuned" in the sequel but still not pushed on a naive player as a core verb, right? Like we had b-hopping in quake 1 and this isn't that dissimilar

Fair assessment, like the rocket jump. Which opens the (interesting to me) conversation up about design intention vs. player application and "discovered" gameplay which segues into an (even *more* interesting, to me) conversation about how far design should let naive interactions guide ongoing dev..