Earlier quoted context omitted.
Many working programmers don't know / use this technique. I bet it was even less used 20 years ago, it took a while till people realized what a revision history could be used for. Even if people know / use it intuitively, there's a value to describe it more formally and give it a name.
20 years ago, at least in my circles, it was ubiquitous. Because we did it manually, no one had the time to linearly search out a regression. (BTW sccs was 1972; no doubt it had predecessors. Before disks were large enough to hold multiple versions of a source tree we kept them on tape)
In my circles, it's not ubiquitous even today.
> BTW sccs was 1972
Many projects didn't use a reasonable versioning system until 10 or 20 years ago.
Before decentralized versioning system, this technique was highly impractical - in one SVN project I worked on, checkout of a branch / revision took ~30 minutes.
CVS tracks commit on individual file basis, checking a global state of the project at a particular timestamp wasn't that trivial / necessarily correct.