What's impressive for a human and for an AI are two different things.

Magnus Carlson had a peak ELO rating of almost 2900.

Would you be impressed with someone with an ELO of 3700?

Would you still be impressed if I told you it was Stockfish?

OpenAI didn't go looking for a tough-for-an-AI problem to solve - they went looking for one that looked like it was easy since it they had heard it had already been solved.

Do you find this impressive?