Why should a stored procedure's logic get the same review and version-control rigor as regular application code?

Because it's still real business logic, just living outside the application's normal codebase — it lives in the database instead. Treating it as an untestable black box because it isn't Java code misses that it needs the same code review, versioning (via migration tools like Flyway/Liquibase), and testing discipline as any other significant logic in the system.