Version control was virtually unknown outside UNIX systems, though, and, in lieu of it, mainframe/PC/Mac developers resorted to barbaric practices which included file tree renaming (v2, v1_John_is_an_idiot), countless zip files with similarly meaningful names with snapshots of entire projects and stuff like that. Then commercial version control systems started popping up, and they were very expensive, usually buggy af, and had no feature parity across themselves, i.e. knowledge of each was not portable.

Whereas nearly every UNIX installation included version control systems for free (SCCS in AT&T UNIX SVR1-4, RCS in BSD UNIX or both) that worked exactly the same everywhere.