I'm sure the posted tweets were a joke. We've seen it before: "I just found out Paul McCartney was in another band before Wings!"
The gag works because it lets us feel superior to kids who seem to think Kanye has a talent beyond self-promotion. Truth is, all the teens (and some pre-teens) I know are well-aware of who McCartney is, as well as the Beatles and Led Zeppelin and Pink Floyd. Sadly, they typically do not know Ravel, Tchaikovsky, Holst or Wagner.