Like someone said earlier, for who though? Many believe they pretty much sound the same, it ain't really difficult making 5 decent projects if they all sound the same. And tbh thats not enough for having a great discography.
Nas can drop as many decent albums as he wants, he still has a long way to come if he wants to be up there with the likes of Outkast, Kanye West, Kendrick Lamar, The Roots, A Tribe, as far as disco...their albums transcendend rap music and are all time music classics. Nas only got 1 of these albums that really transcended rap, and thats Illmatic (probably the best rap album ever though). These other dudes, while not having released the bible of hip hop, are being discussed by their peers, critics, fans, everyone, for having multiple music reference albums, and without any mistep.