This whole post seems to be a conjecture about what quantum mechanics really means.

What we know about quantum mechanics is summed up in the equations. Interpretations of quantum mechanics aren't arguing about the equations, or the predictions of the equations. They are arguing about what it means that these equations give these predictions.

The important thing here is to understand what exactly these interpretations of quantum mechanics are talking about. They aren't talking about the scientific predictions, as all the interpretations are of the same equations, and necessarily predict the same behaviour. By the same token they aren't talking about anything we might see in the universe, as all the various interpretations predict the same observations.

Now sometimes people do propose new theories about the quantum world that lead to different predictions. These aren't interpretations of quantum mechanics, they are new theories. Interpretations are attempts to talk about the current standard theory in the most helpful way.

As far as I can tell, creators of interpretations are looking at the elephant which is quantum mechanics, and discussing whether all angles from which to observe the elephant are equally good, whether some are better than others, or whether only the view we can actually see ourselves is the only one that truly exists.

Now it is useful to try and find new ways of looking at the elephant, as maybe some views are better than others, and someday we might have data that moves us to a new theory where viewpoints that seem equally good now are shown not to be. But right now there isn't any such information, and so we can't really say that one view is better than another. Saying that one answer is better than another, in the absence of relevant information, doesn't seem helpful.

That's the basis on which we prefer many worlds (all outcomes allowed by the equations exist) to collapse (there is only the outcome I can see). It's part of the general principle of not making up complicated explanations on matters where evidence is lacking.