That's a good idea. We might incorporate such a system. Blockchain-based recommender systems have also been proposed in theoretical scientific papers: https://www.researchgate.net/profile/Remo_Frey/publication/306119856_Collaborative_Filtering_on_the_Blockchain_A_Secure_Recommender_System_for_e-Commerce/links/57b2f08c08ae030fe246b851.pdf

However, for now, the protocol still doesn't include that feature. Something like that could be really useful to add in future protocol versions.