No idea, but as a kid, I remember the first time seeing someone getting roasted (on HBO or something like that? It was pretty racy for broadcast if so) and thinking, “how are they not in a fight right now”? It was scathing. The stuff that goes on at these things (award shows) usually seems very much the “lite” version of that…maybe the roasting thing involving mostly/all comedians is more scathing because they have thicker skins from years of hecklers and the way they talk to each other, and it’s more “inside baseball”?
All I can say is - I’d be terrified to roast the likes of Frank Sinatra… 
