I'm sorry mate, but who are we to decide what should or shouldn't exist?
Artists make music to express themselves, and for other people to enjoy.The fact that certain bands' ideas and music are unappealing or offensive to you, doesn't mean they have no right to exist.
I'm exaggerating the following on purpose, but imagine for instance that a group of demented art experts suddenly decides that all of Rembrandt's paintings are offensive to their senses, and must be burned, or should be demoted from their status as great art due to the sudden revelation that he ripped off techniques of other painters while making his art. I mean, that's just nonsense, right?
A music album is like a painting, and you either like/understand what it expresses, or you don't.