Because all tourney matchups have items on.Indeed. I main (mostly out of fanboyism) Sonic (though I haven't played for a while,) and he has an UBER FS. Sonic is VERY decent in item matches, because Super Sonic is a beast. Plus his smash doesn't require you to get up close and personal to your foes, unlike many other FSes.
His Smash does require you to get close and personal to your opponent, it doesn't have the best horizontal range in the game, it doesn't have the lowest start-up or ending lag, and it doesnt kill at very low percents, it's a decent smash at best.