[lmm]

Writing my business logic with no libraries, no standard testing framework, and a syntax and overall feel comparable only to COBOL? No thanks.

(Some databases allow writing stored procedures in other languages, true, but that means a nonstandard interface, tightly coupled deployment model, and testing is still awful)

[funcDropShadow]

There is e.g. https://pgtap.org/ as a testing library for Postgres.