Ali beat George Foreman in his prime, and beat Joe Frazier twice. Tyson was in his prime when Buster Douglas made him look bad, if Buster Douglas makes you look like a fool, what is an Ali going to do to you? Ali was a champion in probably the greatest era for heavyweight fighters, any top ten heavyweight from his era would be
champion now. Tyson dominated a bunch of 2nd rate fighters for 4 years. The guys who beat him would have trouble cracking the top ten in Ali's day. I would guess those
who voted Tyson aren't old enough to have seen Ali fight and to have watched the guys he beat fight other fighters. Short armed lunging Mike Tyson would have never
laid a glove on Ali, and Ali could take a punch a lot better than most people think.
A better question would be Foreman vs Tyson, or Frazier vs Tyson, Ali would have been a bad match up for him.