Two important advantages [...] over their last-century forebears like SCCS, RCS, CVS, SVN, VSS, etc. are this.(1) No advantage. Why? Because contrary to Git propaganda, all commits in Subversion are atomic. A commit in Subversion succeeds or fails. There is no in-between.
(1) atomic commits
(2) branching speed
(2) Not relevant. Why? Because contrary to Git propaganda, branching in Subversion is very fast.
Do note that most of this propaganda was written by someone who openly admitted that he never even looked at Subversion based on a sentence containing the word "RCS" that he picked up somewhere and didn't understand properly. And, his fanboys.
These claims are simply untrue.
EDIT: Note that for example the GCC project uses Subversion. If branching or working with hundreds of developers was really that forbidding, then honestly I wonder how they're doing it.