Why does Kathy Hate the Kardasians?

Serious question, not sarcastic. During the clips of season 12 before Kathy's meltdown it was stated that Kathy was upset that Rinna had ordered Kylie's tequila, and Kathy was shown muttering about hating the Kardashians. I cannot stand anything Kardashian related so I don't read anything about them but those clips piqued my interest. What is the backstory between the Hilton's and Kardashian's or is it just 2 likes not getting along?