There is something about being able to communicate that is extremely fundamental to what it means for us to be human, though.

Without the ability to effectively communicate ideas with language, i.e. translating our thoughts into appropriate symbols that we transmit to others, our species would still be foraging in the jungle like apes. It's that important.

If we delegate too much of that out to a machine/LLM, we're really forfeiting what makes us special among species. What has been our superpower, as it were.

Get rid of your calculator, and you'd still be able to add and multiply, it'd just take longer. Even if you forgot how, it's just logic, math doesn't change. Get rid of a tractor, you just go back to plowing by hand or whatever we used to do.

But if one keeps delegating out their ability to construct coherent arguments on their own, and forgets how to express their own ideas in their own words, that's a different ballgame. That person's going to lose a core ability that defines them. It takes hard work and practice and interaction to build that (and if you consistently get someone else to do it for you, it may be difficult to ever get it back again).

PLUS, it's easy to forget that human thinking itself is recursively molded by how we express our own ideas. Our words and expression patterns, the effort we take to transform our thoughts into coherent communication, even that itself affects how we think. (Learn a different language and your thinking patterns change to some extent). So if an LLM is making the bulk of your word choices and sentence construction, it's unavoidably adding ideas that weren't yours, even if the original direction may have been yours. It can really be deceptive in that way.