"But anything beyond writing a simple function always leads to useless junk."

If that's the article writer's experience then they are simply using it incorrectly. The author seems to suggest most of their usage involves pasting code or chatting via the text interface, likely with a non-sota model.

It would be surprising to find that someone using e.g. Claude Code cli with full access to a codebase and carefully considered prompts is always getting useless junk.