Of course not; there is also the hypothesis that the wavefunction only evolves according to Schrödinger's equation.*, as opposed to the combination of Schrödinger's equation and collapse.Even wavefunction taken as all there is doesn't yield MWI, so, yeah...
I suppose MWI doesn't become interesting, though, unless you consider the additional hypothesis that quantum mechanics remains valid on larger scales -- e.g. that the decoherence seen in measurement is a result of quantum thermodynamics.
If you want to keep insisting that MWI is equivalent to trying to insist that all probability distributions are uniform, that's your problem not mine.
* or whatever the appropriate notion of state and unitary evolution is needed for the particular variant of QM being considered