The Luccheses (which Paul Vario was a member) were some of the biggest junk guys going back to the 50s.

money is the loophole, Always!!!
Goodfellas was long enough and Pesci's Desimone potrayal was just enough to be convincing and sorta likeable, telling the total truth in movies can make it too convoluted and sometimes doesn't make fit the narrative they want to come across in the film