I am decent at chess but barely know how the pieces in Go move.

Of course, this because I have spent a lot of time TRAINING to play chess and basically none training to play go.

I am good on guitar because I started training young but can't play the flute or piano to save my life.

Most complicated skills have basically no transfer or carry over other than knowing how to train on a new skill.

I don't think thats true. If you'd only ever played Doom, I think you could play, say, counterstrike or half-life and be pretty good at it, and i think Carmack is right that its pretty interesting that this doesn't seem to be the case for ai models