Even if we all agree this is true, you still have to think practically. If we don't give a big incentive to turn on your co-conspirators, no one will turn and you might not be able to convict any of them.
As I understand it, intent matters a lot, and that is typically through the testimony of people who had access to SBF in an environment where he was comfortable speaking candidly.
Those people are often accomplices. Sometimes the medium large fish get off if they chop up the big fish.
There are the way things should be, and there are the way things are.