This.

Additionally, the author seems to build an app just for the sake of building an app / learning, not to solve any real serious business problem. Another "big" claim on LLM capabilities based on a solo toy project.

I'm not making any claims about LLM capabilities. I'm making a claim about how most people USE them. The author's own experience proves the point. The moment they stopped prompting and started designing, the output quality jumped. That's not an LLM limitation, that's a workflow problem.