What we're "talking about" here is that Nas was New York's rap wonder kid, considered the next Rakim skill wise along with being immensely popular among hip hop heads in the Mecca of Hip-Hop before Illmatic was released.
"When Nas debuted in 1994, he was quickly labeled the new Rakim. But he was a new kind of beast — try Rakim, Slick Rick, Kool G Rap and KRS-One wrapped into one MC. He was grungy and unrefined, but prolific. Although Wu-Tang Clan, Buckshot from Black Moon, Snoop and Tha Dogg Pound were spitting at the time, upon Nasir’s arrival, it was clear that he was special."
So no matter how you spin it, despite the lofty acclaim & praise Nas received before Illmatic's debut, mainstream hip hop consumers weren't checking for Illmatic initially after it's release, which was ultimately a