I don't think SQL can be more brittle than untyped object-oriented Python. The latter is as brittle as it gets, as we all know from ML code. SQL is common for ETL exactly because it's not brittle, (mostly) declarative and easy to test and modularize.
What Python give you is more flexibility, at the expensive of exponentially more brittleness.
What Python give you is more flexibility, at the expensive of exponentially more brittleness.