I don't agree with crediting the bombs entirely but it's equally dumb to discard them. Just one of those bombs left Big Mom in this state:
And the explosion should've taken place at the bottom of the pit that Law made yet its impact outside the pit was bigger than Onigashima:
The explosives definitely played a huge role in Big Mom's defeat.

And the explosion should've taken place at the bottom of the pit that Law made yet its impact outside the pit was bigger than Onigashima:

The explosives definitely played a huge role in Big Mom's defeat.