With increasing pressure put on the mobs on all criminal activities, the mobs found they couldn't recruit new, dependable members without the promises of huge profits—far more than the rewards to each individual from gambling or loan-sharking. The boys were therefore allowed to "sneak."
The dangers from dealing in junk remain for mafiosi: Monumental prison sentences can force newer members to crack under pressure and name other mob guys. The answer by the new ruthless mob bosses is quick death sentences for likely squealers.
It may be that the unofficial policy of turning a blind eye to sneakers will prove to be a deadly Achilles' heel in coming years for the mobs. For now they have little choice. Perhaps further cooperation with non-Mafia gangsters by extending an okay for them to operate for an increased Mafia tax might work. It is a dangerous gamble, but the mobs can live with these kinds of risks.