I don't know that this is a very persuasive argument. We have all sorts of complex, technical "laws" (both in statutes and agency rules extending those statutes). A lot of them are important and sensible.
In a field like finance, once you make something illegal, doesn't the prosecution's argument pretty much come down to:
1. Under the US code, foo is illegal. That's the rule that everybody working in this field has to play by.
2. The defendant fooed, flagrantly and with relish, and in the process made umpteen zillion dollars.
3. At all times, the defendant made it clear that they knew fooing was wrong. For instance, when discussing fooing, they logged into each other's email accounts and wrote drafts rather than sending emails, and shredded their birth certificates after discussing foo.
4. As a result of all this reckless fooing, which we remind you is illegal in the US, 3,392 people lost their houses.
A jury can't follow this argument?
An argument I've read more frequently is that the laws around this stuff aren't clear enough, so that a defense attorney can hopelessly muddle up a case by arguing "we weren't fooing, we were clearly barring". We could make the laws a lot more clear! But in doing so, we'd potentially disrupt the economy, and so it's a tricky balancing act.