LLMs mostly only being code-writers was true a year ago, but it is not true now. Now they are tool-callers, which means a coding agent can effectively: run lints/typechecks/tests (and fix resulting errors), dig into observability platforms to identify root cause of isses (e.g. on Sentry or similar), run benchmarks to identify slow code / hot paths, keep systems up to date by reading migration docs (and applying them) for new majors of consumed libs, etc.

So sure, if you have none of these things set up to back-pressure agents and help them better understand the system, then they will just be dumb LLM code writers. But you can definitely go a lot further than that with the improvements that are rapidly happening to models and harnesses.