Many worlds is an interpretation. It is an untestable explanation of the evidence, there is no way to decide between many worlds and other models (besides, perhaps, convenience). It is not physics, but metaphysics.
I know some people are pushing many worlds with religious fervor and it is obnoxious. But as far as I know, despite the horde of internet acolytes that gives MW a weird thought-smell, it is still a mainstream interpretation and nobody is "prosecuted" for it.
Many Worlds is the theory that best fits the evidence of quantum experiments, keeping in mind Occam's razor. In fact, it is the only comprehensible one. Wave collapse is comparable to epicycles in that they are both attempts at harmonizing completely contradictory evidence with a preconceived common-sense assumption (single universe and geocentrism, respectively).