Common people go to such sites for updates from friends, or to follow celebrities.

Their friends will start using more and more AI, ans celebrities will become all AI.

Why read a friend's page, if it's just AI drivel. Same for a celebrity.

It doesn't even need tp be true. Burned once, people will never trust again. The humiliation of writing messages that your friend only has a bot summarize, and reply to, will kill it.

Imagine you speak to your friend, and they haven't even read any measages you wrote, but their AI responded? And you in turn. Imagine you've had dozens of conversations, but it was with a bot instead of your friend.

Your trust will be eroded.

SPAM doesn't act like your friend. A bot does.

And the inability to distinguish will be the clincher. And yes, you won't know the difference, not after the AI is trained on their sent mail folder.