After Joan Rivers' death, Kathy Griffin seemed like her only natural successor, but it was obvious to most that - from the offset - Kathy wasn't exactly embracing the gaping role. She often spent her time on the show muted. Rivers delivered cutting lines, and it was accepted and usually welcomed because of what she represented. No one could take up her mantel. When people tried, they failed miserably, as Giuliana Rancic spectacularly displayed. 

That incident led to the departure of Kelly Osbourne, and now Kathy Griffin. By way of explanation as to why she also chose to leave, the 53-year-old tweeted the below. 
  

Regarding Rancic's "joke" regarding Zendaya's hair, Griffin had previously told the Chicago Sun Times that she “wouldn’t have said the joke in the first place.”