You should entertain all predictions of a physical theory. That's how you test and possibly falsify them. Multiverses are an interesting intellectual exercise,

You should entertain all predictions of a physical theory. That's how you test and possibly falsify them. Multiverses are an interesting intellectual exercise, but are they the only way to "solve" the specific problems we're encountering in physics? If not, then presumably there is at least one single universe theory with different properties that might yield different insights instead of sweeping the inconveniences into different universes. Those different properties might even be testable. It just doesn't seem like multiple unobservable universes actually gives you anything actionable where single universe theories might.