But really, so what? We already have specialised chess engines (stockfish, leela, alphazero etc) that are far far stronger than humans will ever be, so insofar as that’s an interesting goal, we achieved it with deep blue and have gone way way beyond it since. The fact that a large Language model isn’t able to discern legal chess moves seems to me to be neither here nor there. Most humans can’t do that either. I don’t see it as evidence of lack of a world model either (because most people with a real chess board in front of them and a mental model of the world can’t play legal chess moves).

I find it astonishing that people pay any attention to Gary Marcus and doubly so here. Whether or not you are an “AI optimist”, he clearly is just a bloviator.