Why do LMMs overuse these patterns of speech that aren't overused in the wild?

Here's a quote:

> "That’s not neuroscience — that’s cargo-cult reasoning wrapped in academic buzzwords."

I think most of us who use ChatGPT would immediately recognize this as being AI-generated. It's perfectly valid English and we could all imagine a real human saying it, but ChatGPT (or maybe LLMs more broadly) seem to have landed on certain patterns like this one that they use constantly. Is it some kind of overfitting? Post training where a biased toward this pattern was introduced? Something else?