Git also allows you to push --force if so you wish, something that would require a 51% attack if you were to do it in a blockchain-based ledger.

I really don't think blockchains are a panacea and in many cases they're a solution looking for a problem, but that doesn't mean they're necessarily useless.

EDIT: Also as a sibling parent said, it's just proof of work what gets the bad rap about power consumption, and there's nothing inherently costly in blockchains themselves.