Beside the already known accusation of xrp being a centralize project working with banks (something that is the opposite of true crypto) and not very transparent with the overall conduct of the project I don't think am aware of any other season why people hate the project just by mentioning the name.
I don't understand it as well, because I also never invested in this project base on this community dislike, xrp is not only the centralize project in the space but for some reason best known to the crypto community, it is the most hate.
That is basically all there is to it. I mean I have been in crypto for 9 years now and never owned a single XRP in my life, why? Only because of the reason you already mentioned. If something is so centralized that they are saying "use our coins so that we could make money from companies" type of deal, then we shouldn't even be considering them legit.
We are talking about a scam project that scams people so greatly that people are not even aware that they are getting scammed. Honestly, I would never own any XRP but I have to congratulate XRP creators, they have done something that nobody else achieved so far, turning a scam into a long term real project.