So any pirated content you'd download 20+ years ago was almost guaranteed to be RAR archived. Or sometimes even WinACE [1], anyone remember that one? It was awesome as well. Seems like the early 2000's was a war of compression formats similar to VHS vs Betamax decades earlier.
If you go on older established torrent trackers you can still find original torrents/content archived in RAR or ACE formats. Like Disney's Hercules for example.
BTW, I just tried it out of nostalgia and the OG WinACE app still works on Windows 11 today.
If you encrypt ZIP file - then filenames aren't encrypted, only content.
For users, it was not an issue since they don't have to worry about licensing and whatnot.
WinRAR was also a fun target to write your very own crack for it. You could crack it multiple ways a well: remove the dialog and change texts, patch it to think it's licensed or write a keygen.
That was HUGE for the emulation scene before 7zip, consider an SNES game:
1. JP version
2. NA version
3. PAL version
And possibly 1 or more revisions of each of the above.
With RAR the size was often not much more than if a single version was compressed. Not so with ZIP
Spanning is old as dirt, I remember doing it with pkzip and floppies so I don't think it is something unique to RAR.