Many organizations use Subversion (or SVN) as their version control system (VCS) of choice. Often, SVN is so thoroughly baked into the organization’s processes—with build scripts, commit hooks, custom tooling, etc.—that it would be prohibitively expensive to change to a different VCS.
There’s nothing wrong with Subversion, but sometimes you want the power of Git. I personally prefer Git’s ability to commit locally and its branching model over SVN. Git can bidirectionally interact with Subversion repositories with the
git svn command.