An increasing number of us use a clever coworker's git-atop-perforce bridge,
so we feel like we're working in a git world, but certain operations sync to
Perforce and use the many perforce presubmit/postsubmit checks/scripts/etc,
enforcing normal code review processes and such.
So with stuff like that, or git-svn, if you're going to have a blessed
"central" repo anyway, who really cares if that repo is actually git, svn,
perforce, etc, as long as you can use your DVCS of choice at the edge?
The alternative is changing years of accumulated tools & checks every time a
new VCS comes out and you change your master repo's storage format.