A more accurate phrasing is: It's significantly less likely that one learns the portion of the work they offload to an LLM.

A random anecdote is that most of the people I know who went very far in theoretical math are relatively poor at basic mental arithmetic, because they always think in the abstract and offload addition and multiplication to the calculator. It doesn't mean they can't do it, they just aren't as practiced or as fast at it.

Just like how you significantly increased the difficulty of exams in "open book" exams in the past where the only way to pass the open book exam was to know the material well, you similarly need to increase the difficulty of other work where it won't matter if you have an LLM, because you won't pass without knowing your shit either!

They learn if they have to, like we always did. In-person exams (proctored) are good for testing that.