I think I finally figured it out. That is, the reason why AI written articles suck:

Both the author and I are reading the article for the first time.

When an article is insightful I don't even mind the emdashes or that the stark truth is not X, but Y. A good take can transcend even llmism. But then you have questions, and somehow the author doesn't even know what you are talking about, it's simply because they are discovering the insight at the same time you are.

They were busy, they didn't have time to write. As a consequence, they only dedicated enough time to skim the result before publishing. They don't know what's in it. You can't ask them what they were thinking when they came up with the insight because, well, they didn't think.

The great article sucks because there is nobody behind it.