There are two forms of argument that are helpful and healthy for human society.
The first form is dialectic, whereby two (or more) participants engage in one another in a mutually cooperative search for truth in regards to some subject. It is traditionally the method characteristic of philosophy and the special sciences which philosophy gives birth to. It is rather obvious that BF SD could not be considered representative of dialectic. There is nothing remotely similar to cooperation between posters, and nobody at any point appears to entertain the prospect that they are incorrect and their opponent correct, which is the foundation upon which the dialectical method is built.
The second form is rhetoric. Rhetoric is the art of persuasion, and in a democratic society based on public participation, any citizen, in order to fully perform their function as a citizen, has to be equipped to some degree or another with rhetorical skills. Dialectic can not really be engaged in on a society wide scale, but rhetoric allows us to get around the challenges inherent to dialectic and yet still have a society based, to some degree, on reasoned exchange. Is what goes on in SD representative of rhetoric? Obviously, no. At no point does anyone attempt to persuade anyone else of the truth of their positions, nor are their arguments persuasive, unless one comes in wanting to be persuaded. Rather than tailoring arguments to persuade their opponent, SD arguments are tailored in such a way as to give the person making them an excuse not to be persuaded, and to continue hurling insults at their opponent.
If what goes in in SD is neither dialectic nor rhetoric, what is it? It is simply forum sanctioned fighting. A place for people to go to hurl insults at one another and express internet rage. It is not helpful to the forum in any manner, and should be closed.