I think both your statement and their statement are too strong. There is no reason to think LLMs can do everything a human can do, which seems to be your implication. On the other hand, the technology is still improving, so maybe it’ll get there.

My take is that:

1) LLMs cannot do everything humans can, but

2) There's no fundamental reason preventing some future technology to do everything humans can, and

3) LLMs are explicitly designed and trained to mimic human capabilities in fully general sense.

Point 2) is the "or else magic exists" bit; point 3) says you need a more specific reason to justify assertion that LLMs can't create new concepts/abstractions, given that they're trained in order to achieve just that.

Note: I read OP as saying they fundamentally can't and thus never will. If they meant just that the current breed can't, I'm not going to dispute it.