I like the novelty/predictability ratio idea. There is also the idea of “create expectations and satisfy them”, which leads to a sense of stability. Our cultures and genres create expectations. Rhymes tied to a certain metric can become part of these expectations. Of course, you can also create expectations and frustrate them, which leads to a sense of instability. Searching for “fakeout rhyme” videos makes this evident. Pat Pattison, an expert in songwriting, could be a good source on this ☺️
I see your concern for truth in any scenario, and I agree validity should be a constant consideration! However, bias and astroturfing are different. Bias is the lens that we use to look at reality. Astroturfing is forcing lenses onto many others without them knowing. It is a deliberate campaign.