For the same reason the things listed above are popular may be the reason why the most popular LLM ends up not being the best. People don't tend to buy good things, they very commonly buy the most shiny ones. An LLM that says "you're right" sure seems a lot more shiny than one that says "Mr. Jayd16, what you've just said is one of the most insanely idiotic things I have ever heard... Everyone in this room is now dumber for having listened to it. I award you no points, and may God have mercy on your soul"
I disagree. What's new is that this flattery is individually, personally targeted. The AI user is given the impression that they're having a back-and-forth conversation with a single trusted friend.
You don't have the same personal experience passively consuming political mass media.
Village idiot used to be found out because no one in the village shared the same wingnut views.
Partisan media gave you two polls of wingnut views to choose for reinforcement.
Social media allowed all village idiots to find each other and reinforce each others shared wingnut views of which there are 1000s to choose from.
Now with LLMs you can have personalized reinforcement of any newly invented wingnut view on the fly. So can get into very specific self radicalization loops especially for the mentally ill.
I would have downvoted your comment, except you can't downvote direct replies on HN. ;-)