While it may be enticing to think of a flamewar as a crucible for good discussion, I think that it's far from the case. Fierce, passionate criticism is not the same thing as people talking past each other to attack straw men. There's little time or incentive to sift through the ashes looking for some purified argument that's withstood the flames when you can rush into the next thread in the forum where the a new fire is just getting started. This is pretty clear to see when the same ideological discussions are rewarmed again and again.