This is kind of like saying a kid can never become a better programmer than the average of his teachers.
IMHO, the reasons not to use AI are social, not logical.
The AI doesn't know what good or bad code is. It doesn't know what surpassing someone means. It's been trained to generate text similar to its training data, and that's what it does.
If you feed it only good code, we'd expect a better result, but currently we're feeding it average code. The cost to evaluate code quality for the huge data set is too high.
The kid can learn and become better over time, while "AI" can only be retrained using better training data.
I'm not against using AI by any means, but I know what to use it for: for stuff where I can only do a worse than half the population because I can't be bothered to learn it properly. I don't want to toot my own horn, but I'd say I'm definitely better at my niche than 50% of the people. There are plenty of other niches where I'm not.