It’s either a testament to OutKast’s skill as musicians, or a sad statement about how small the pool of mainstream pop music was in the early 2000s, that they’re the only band to win three of our year-by-year polls. Even the Beatles only won one outright and tied on a second.
Oddly enough, the song of theirs that I recall getting the most airplay back then, “The Whole World”, never made #1 and seems to have been largely forgotten today.