Also, was the slightly-below-average person actually good at basic mental arithmetic before? Or did they just work through simple problems agonisingly slowly or accept the answer the other person gave them even though it was wrong and left them shortchanged?

> What makes those "basic maths" a good benchmark for whether we're fucked?

They weren't saying basic maths was a good benchmark for whether we're fucked, they said that if GPT does for every other skill what calculators did for basic maths — viz. make us forget all the fundamentals and rely on computers for everything — we're fucked.

My personal opinion is that sometimes our head space is maybe a little too freed up by tool-assisted thinking, and we lose the ability to focus and concentrate.