> What's the actual criticism here

I stated this in an earlier post: "Probably what matters more is the specific process."

> Is the idea that getting enough sleep is healthy also a "meme"?

Yes actually.

> That Alzheimer and cancer suck and have no upsides?

Maybe? I don't think that qualifies, It's more like an emotional response to a disease.

> What is "memeing" in this context?

Repeating memes. In this case "writing is thinking" is a meme in the culturally transmitted idea sense. I don't think it qualifies as thinking because it's just the mechanical propagation of those memes through the culture. So if we're going to classify that and all other stuff one writes down as thought and elevate it, I don't see why prompting an AI isn't among that.