there are bands who have made it in our local scene, such as Electrico, the suns, ronin and rudra(headlined a couple of metal festivals in europe, these are huge affairs there). I am sure at one point of time or another they must have had some form of guidance.
leaders are not necessary in bands, unless you're talking about concert bands or military bands. All you need is someone to take initiative to organizing the band together.
Explosions in the sky doesnt have a leader and yet they are as succesful as they are, fame doesnt get in their head either. But having said that, direction is fundamental for the success of the band.