Because it wasn't pre-AI. It was normal for people to post links as arguments, counterarguments, etc. It annoyed me, and I didn't bother clicking most of them, and would occasionally tell them "If you can't bother articulating your thoughts, I can't be bothered with that link".
But I was always in the minority. If that behavior is acceptable to the masses, so is AI generated content.
(And, BTW, the "link as argument" bugs me a lot more than AI responses. If I know the person, I can assume the person has done some due diligence in reviewing the AI response before sending it to me.)
> If I wanted the LLM to teach me (thank you, no), I would ask an LLM. I'm reading your website/newsletter/email because I want to hear from you.
To play the devil's advocate: it's far from a given that had you asked the LLM it would have given you a comparable response to the one you got. You're precluding the possibility that the other party instructed the LLM to write what he intended to say.