Why do the various LLM disappoint me in reading requests?

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Serious question here. I have tried various LLM over the past year to help me choose fictional novels to read based on a decent amount of input data. I thought this would be a task that fits well into the LLM model but I am constantly disappointed in the suggestions. They are either vastly different from what I requested or complete hallucinations of book titles and descriptions that don't actually exist. Is the major problem here the training is done on very popular books such that the LLM p...