"Famously bad" is an opinion cloaked in adverbial authority. Plenty of people like both, and even if they don't like them, they think better in one vs the other.
SQL is ok, it just needs to be refined a bit. This was such an opportunity but they didn't cease it.
That git(1) (the user interface) is badly designed is an opinion shared by many people, including many on the Git mailing list. Backwards compatibility is mostly used to argue for the status quo, not that the status quo is good.
All the more reason for alternative interfaces.
I like your phrase “adverbial authority”
For Me I Think SQL is great for most of the features here and the most important is that people don't need to learn a new full language to use GitQL