LLMs are an approximation of all the human media they consume. An LLM cannot exist with out human circuitry. It's at best an ersatz language user.
The fact that LLMs trained on dumptrucks full of data cannot achieve what a middle schooler begrudgingly achieves using existence and snide remarks.
First and foremost (and what I think the parent comment is getting at) whether you could truly say an LLM "understands" language
As a secondary quibble in the context of the parent post, though big overall, I would argue that the whole argument is moot since a human couldn't possibly learn the way an LLM does in a single lifetime