Clearly they instructed Claude to always give points to improve regardless of if the text is good enough for its purpose

It's worse than that. It's just a word prediction algorithm. When you ask someone for advice, it's very common to say "this part could use improvement" so that's what AI is going to say to you. It doesn't matter if you feed it a text to a friend, or your Knuckles the Echidna x Naruto fanfiction, or The Left Hand of Darkness, it's always going to respond the same way. It's not critiquing anything, it's simply imitating critique.