I've noticed a similar pattern. AI assistants are incredible at kinetic coding i.e. generating boilerplate, refactoring, writing tests. But they are detrimental to potential coding especially at the architectural thinking that happens before you touch the keyboard.

Writing by hand (or whiteboarding) forces you to load the entire context into your working memory. AI allows you to be lazy with your working memory. The code gets written faster, but the mental model of the system in my head is significantly weaker.

Definitely, it's great at making a template but, it's hard to see or continue from what it has generated.

I agree that writing by hand sets up that mental model, and because it's written by you, it's easier to branch out from there.