Most of this critique hinges on the author not being skilled in the practice of using LLMs to produce good writing outputs.

ChatGPT is a bad writer, and is the wrong tool for copy writing. That is a consequence of its post-training, though. I don't expect this to be true forever.

Using Claude or Writer would produce better outputs by an unskilled hand. And even with ChatGPT it's possible to get good outputs if you know what you're doing.

This implies that perhaps there will still be a role for copywriters as skilled users of LLMs. Though, I think it's more likely that the service of copywriting will transform copywriting products that centralize LLM know-how and expose simple self-service tools.