Part of my reasoning is that rsync is specifically made for this kind of thing, whereas git is specifically made to synchronize coding among multiple developers. So my argument is partly theoretical and less practical.

But for an argument based in pragmatism, rsync has tools such as the --delay-updates flag, which allows your entire deployment procedure to become a pass-or-fail atomic operation. This kind of assurance slows my hair loss as a systems administrator. AFAIK git has no such tools, but I'm certainly open to being corrected.