Precisely. Longevity is part of greatness. Kareem had longevity on the court...Jordan didn't. Kareem didn't need time off...actually he probably did, because he suffered severe migraines, but he never took the time off. Kareem was a major contributor to title-winning teams in his 18th and 19th years.
We'll never know, will we, since Jordan didn't play for 20 straight seasons. Also, wasn't Jordan's knee pretty well trashed at the end of his career (playing 2/3 the games that Kareem did)? We don't even know that he could have played as long as Kareem did.
But here's what we do know...Kareem played for 20 straight seasons (plus three years of college before that), and Jordan didn't.
And that's what makes what Kareem did all the more impressive. He accomplished what he did while not always being the primary focus of his team.
Except that this isn't a valid method to determine greatness, because it doesn't account for career longevity. And even if you did look at career average numbers, it's not obvious that Jordan was clearly the better player. Although, Jordan scored about 20% more points per game, Kareem was a better FG% shooter. If Kareem had taken as many shots per game as Jordan did, with his better FG%, Kareem's PPG would have increased by 5.2 PPG (if my math is right), and be nearly identical to Jordan's.
Kareem nearly doubled Jordan's rebounding average. Jordan had more steals, while Kareem had more blocks.
There's more to the game than just high-flying dunks and scoring points.
........G....FG...FGA..FG%..FT.FTA..FT%
Kareem 1560 10.2 18.1 .559 4.3 6.0 .721
Jordan 1072 11.4 22.9 .497 6.8 8.2 .835
........TRB.AST.STL.BLK.TOV.PF..PTS
Kareem 11.2 3.6 0.9 2.6 2.7 3.0 24.6
Jordan 06.2 5.3 2.3 0.8 2.7 2.6 30.1
