Actually I think it says a lot about how expressive SQL is.
I get why a lot of developers take swipes at SQL - it is a bit different to other languages. But you cannot beat it for what it does.
Another ‘great’ language is XSLT - so far I’ve seen nothing else that comes close for transforming data. It’s just a shame it’s so closely tied to XML which has understandably fallen out of favour
I’m not sure there’s much truth to your statement. There’s nothing inherently complex about git’s internal data structure nor does putting a SQL interface on something indicate a level of complexity.
Next logical step : a kernel level SQL interpreter integrated in systemd.