There are sociological reasons why this happens less with humans:

1. You cycle your dumb repetitive jokes with everyone you meet, so nobody hears it twice

2. Those who know you well will notice when you're just repeating ("dad jokes")

3. As a person's idiosyncrasies are beginning to wear on their social circles, they will be getting small clues to stop saying those things. Agents don't get these social between-the-lines cues to stop a certain behavior, they endlessly repeat. Perhaps between model version releases, frontier labs can harvest the web and ask "What Claudisms do people mention negatively?" but I don't think they do that yet.

Because they are HEAVILY trained to give addictive responses.

They don't want to just answer your question. They want to sycophantically make you feel like a genius for being smart enough to use them.

Real human writing doesn’t follow such strict rules. When the same small set of rules is applied over and over throughout a text, it becomes obviously strange and machine-like.