To Nas fans (like myself) that shit was worse than ether because it put everything in perspective and made Jay look like a dude filled with bitchassness. He made dude seem like he was a snake on the highest level, like dude had no morals. The stuff Nas was saying about Jay in that song, made it so no real dude could even fuck with Jay anymore. That shit was just disgusting, about how bad Jay wanted to be dude, and how he idolized dude. How he was trying to take his spot, and then when Nas takes a break to take care of his sick mother that's when Jay smells blood and attacks.
Basically, Nas destroyed his character and broke down who he was as a man or lack thereof. He destroyed his mind and soul lol. He made JayZ shift from a hip-hop star to a pop "I need to make the charts" artist. It was like JayZ knew he could no longer run the race of the best emcee, so he went another route, and decided to become a hip-POP artist instead.
... Too bad there's no way to tell if Nas was telling the truth about all that shit or if Nas was simply bending the truth like most of us do in a roast session.