The article title makes no sense, and the article itself too.
No one is saying GPT has achieved AGI. Is it a strawman argument?
AGI could end up in a similar predicament: a benchmark, devised by humans, that’s rendered obsolete by the technology it was meant to measure.
Just because we can't measure it doesn't mean it is obsolete.
In a way, human intelligence is like that.
People used to think earth used to be the centre of the universe, because everybody said so. Would you say that only Nicolaus Copernicus was intelligent?