The trouble is that it ignores the very thing that debate is trying to teach: the ability to sympathize with, understand, and argue for a position even if you don’t agree with it. It is meant to encourage a greater understanding of the world through different perspectives.
People do exactly this with Ks in policy debate - the same person presenting a K in one round will be defending against it in another round. Nationally competitive debaters don't (in my experience) choose Ks because they believe in them, but because they're tactically effective.
