I can answer “Vibranium exists in some possible worlds.”
You can? That’s word magic, right?
What you mean to say is that, “In some possible words, there is a possibility of something like Vibranium.”
This is not a statement of inevitability; it is a statement of possibility. It may turn out that Marvel Comics may have been optimistic that the multiple traits of Vibranium could ever co-exist in a single element.
The point of the multi-verse theory is not that Any-Thing is possible, but rather:
“Any thing that is possible, must exist somewhere.”
That is a good refutation of Anselm’s ontological argument, but not that of Plantinga’s one, which involves possible worlds. It is better for a being to exist in all worlds, not just a possible one,
Possible worlds have nothing to do with the multiverse theory, it’s an entirely philosophical idea which entails ‘potentiality’.
Currently the only real issue I have with the MOA is knowing whether or not something can be objectively good.