And you know, Socrates was right. We did lose our memory with writing! How many phone numbers do you remember now that you have a phonebook in your phone? Humans will lose skills due to LLMs. That's just obvious on its face by the fact that if you don't do a skill regularly, you will lose it (or lose to do it as well as you once had).
The real question is whether we're worse off or better off overall than we were in Socrates' Athens.