Just face it: Rexxar is the greatest hero the Horde has ever known. If it were not for Rexxar, Cairne Bloodhoof would have sat mired in depression while the aggressor humans of Kul Tiras destroyed Orgrimmar. Baine would be dead. Thrall wouldn't have acted in time and might well have ended up a Warchief without a Horde to lead. The Echo Isles were saved from destruction years before Zalazane by Rexxar.
It is an indisputable fact. Rexxar saved the Horde, defeated its enemies, discovered the human perfidy and the actions of Admiral Proudmoore (opening Jaina's eyes to her own father's unwillingness to share her dream of peace) -- and, lest we forget, it was no Warchief who struck the ultimate blow in this battle at the birth of the new orc homeland. It was the hand of a Mok'Nathal.