Most other programming languages are more composable than a SQL query. You can make functions, split logic into different classes, extract common logic, etc. Much harder with big sql queries
Some co-workers and I inherited a code-base where the authors went down the views and stored procedures route. It was basicallly impossible to untangle; there was no knowing what relied on a view or a proc, so you couldn’t touch them at all, there were no docs, there were duplicates of everything (and again, no way to know what’s used). A good number of them had all kinds of side effects and weird performance characteristics. They weren’t version controlled.
The issues just kept going.
They can and should most definitely be testable, documentable, trackable and version controlled.
Should one also judge all backend programming by PHP standards circa 1998?
An array instead of a linked list or vice versa. A dequeue instead of a set or vice versa. A binary tree instead of a B+ tree. You can't just throw column names at a DB schema and hope for the best. There's actual engineering to be done, even if many programmers refuse to admit it when interacting with a relational database engine.
Do you have to read about it? Sure, just like all programming languages and platforms. But, interestingly, SQL was designed for non-technical analysts, so (to your point) it's more accessible than those others.
SQL schema creation and maintenance is all about choosing the right data structures for the job at hand.
If you neglect attention to your data structures, no algorithms will save you, and you really only have yourself to blame. It's a still to be learned and honed like any other.