The major organized crime cases of the 70s and 80s were built almost entirely off wiretaps, informants, and a then novel law called RICO which federalized a bunch of former state crimes notably loansharking and gambling and dramatically increased the sentences for those convicted of those crimes. This resulted in dwindling membership and combined with changing demographics is why most mobsters in America are 70-80 years old today.

If anything Italy proves how ineffective these laws are. Every couple of months they announce a 100 million euro Ndrangheta/Camorra related seizure and yet these groups still have thousands of members, still traffic drugs by the ton, and still extort half the businesses in the South.