I don't care about what Amazon does with stars. I just want a 5 star rating for books. You guys can do whatever you want with the system for other stuff... But every book app I've used has a 5 star rating system that I tend to prefer for reasons stated below.

Yup, exactly why 80% percent of the time copying Big Tech UI/UX isn't a graat idea. We have a chance to do something new here, where the user has to perform and understand way less actions. Big tech can only dream of letting their users reply on, zap and share literally everything, so they invented a bunch of proxy features. They had to make these features look and feel like lottery machines because otherwise no one would even use them. We don't have that problem. If you do, you're designing it wrong. Replying, sharing and zapping are examples of some if the most natural UX you can find.