That may be true, but the reason for the five being sent was to put the kybosh on Sauron's evil machinations. And if any were sent to the south of Middle-earth they failed to keep the Southrons and Haradrim from joining Sauron's armies, just as it appears the two Blue Wizards failed to keep the Easterlings from doing.
In the north, two wizards, both also failed their task: Saruman became corrupted in his search for the knowledge of power required to throw down Sauron and Radagast forgot the task in his study of Middle-earth's fauna.
Thus only the greatest of the five, Olorin (aka. Gandalf, Mithrandir, The Grey Pilgrim, etc.) able to sway the hearts of Men sufficiently to keep Sauron from taking over Middle-earth, and even then it took a lot of divine intervention by Eru. For I hold that Eru had to be in the background pulling strings, for all these innumerable coincidences to have happened at the right time and place.
Also, we only know this, because History is written by the winners, and if the others had any part in bringing Sauron's downfall into fruition, we have no record of it, for it was Gandalf's friends who brought us our knowledge of those times.
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