...and Tito is a friend of his.
UFC kept them apart on purpose.
They both were cash cows and in the same class. UFC president Dana White said himself that they were kept apart because he knew Liddell would pulverize Tito. Tito brought as many fans as Liddell so he was very valuable; they had to keep him winning. Finally the couldn’t keep them apart and, as expected, Liddell killed him.