This is true but it was certainly not considered good practise even at the time. I've been on the seller part of a few software companies acquisitions from the early nineties, and checking what kind of source control we were using and how was part of every audit. A long history of sccs -> cvs -> subversion ->mercurial or git...
Yes, though eg Linus Torvalds famously said that them mailing around tar-balls was better than CVS.
No. In the bad old days, for many people version control software wasn't sufficiently better (and in some respects much worse) than just not using any. So many people didn't use any.