In the theoretical universe where banning crypto is possible, yes it would stop almost all ransomware of the scale we see reported in news today.

There's just no other form of payment which would work for them. You can't easily go "can I have $50k worth of giftcards" and on the receiving side you can't easily validate or sell millions of them without tanking the value. Any kind of wire transfer would expose the source immediately at that scale. There's only so much money you can move through services that give you kickbacks of various kinds. What else is left?

Basically unless ransomware teams know of a new really good way of laundering money without a trail, or are happy to take a massive pay cut, that would be the end of most of their operations.