I remember git-svn being pretty commonly used back in the day (circa 2007). At that point a lot of open-source projects were still using svn and if you wanted to use git locally, git-svn or something similar was how you did it.

My first experience with git was using git-svn to work with my company's internal svn repository, which I did for a couple years before the company stopped using svn. There was no internal desire for decentralized version control (rather the opposite, in fact; they wanted centralized permission management and such).