> SQL as a query language is truly horrible once you get past simple data queries.
I think things start to get dicey as soon as you're past basic SELECT, FROM, JOIN, WHERE [1], ORDER BY. CTEs, subqueries, cross joins, case expressions, etc. certainly aren't advanced, but they do surprising things at times, and it can be hard to tell what's going on under the hood with the optimizer. I'd prefer to work with a full-fledged programming language or the underlying primitives the optimizer translates SQL into, but SQL isn't a problem for me personally. The problem is that I've had teammates be utterly defeated by it.
1. And even then you can get in trouble, e.g. not knowing that OR short-circuiting isn't part of the standard, and Postgres for example doesn't do it.
SQL is a query tool. Not a general purpose programming platform. But it is good for surprisingly complex queries on surprisingly large and complex data sets.