You keep assuming that LLM usage is automatically harmful with literally zero reason to believe that, and several anecdotes from people on how they use it positively.

There's simply no reason to even draw a weak analogy to smoking. You'd do much better to draw an analogy to e.g. methylphenidate or amphetamine, which certainly you can abuse and get addicted to, and might even be harmful for the average person (even carrying the possibility of psychosis!), but which carry cognitive benefits with minimal side effects for others.

I'll give another concrete use: the other day I scanned a storybook with my phone and had codex OCR it and compare with a list I've started of words and sound patterns my kid knows how to read so that it could identify irregular words or new sounds for us to go over before we start the story.

Please, concretely, let me know what the adverse effects were there.