My main takeaway, too. Been using Claude on my side project that I have singlehandledly been working on for three years. It works well initially, you catch all of AIs mistakes or unfavorable approaches because you know the architecture in and out. But as you stop thinking about the new features, stop losing touch with all the stuff AI throws at you, you fail to develop intuitive feeling on when and how to abstract and introduce architecture.

Another note was for me e2e tests; while AI can write them it never comes up with just basic organization or abstraction required to manage a large e2e test suite with hundreds of tests. It immediately starts to produce spaghetti code.