I think we're at odds because I'm thinking of developers in general and you are focused on open source work. I don't have stats, but I'd be willing to bet that a majority of code being written is closed source even today. I think this is worth remembering in any discussion about source control.
Subversion was indeed a much better CVS than CVS. And the world almost jumped on it as a standard. But then git appeared. If you were a young person looking at building exciting projects from source, you might never have reason to learn svn. I think that qualifies as "forgotten"