Here, the enormous advantages available to me don't come from the fact that I have access to things that the scientist's don't have access to

You need to keep in mind that they have access to a very, very huge number of things that you don't have access to (and have potential access to more things than you think they do), and can get the taste of the enormous space of issues any of which can demolish the case for MWI that you see completely, from the outside. For example, non-linearity of the equations absolutely kills MWI. Now, only a subset of physicists considers the non-linearity to be likely. Others believe in other such things, most of which just kill MWI outright, with all the argument for it flying apart like a card house in the wind of a category 6 hurricane. Expecting a hurricane, experts choose not to bother with the question of mechanical stability of the card house on it's own - they would rather debate in which direction, and how far, the cards will land.