It prevented people from leapfrogging so they won't grind their mogas.
Now, if you don't have moga cash, you have to level up your moga to the other moga's level, or have a higher one.
There's one thing I don't get.
Yesterday while playing,I ran into a level 14 Yugure.
Sent out my level 12 MoGa[The whale one...named it Moby].
Manged to whittle the Yugure down to the red zone for health and oddly enough,I was given the opportunity to catch it.