I recall that it was Frank Renzulli, one of the key writers in the first two seasons, who wanted the mobsters doing the dirty work themselves. While this obviously wasn't realistic, he felt it was a better way to tell a story. Renzulli was the one who wrote the original Bronx Tale play, and sued Chaz Palminteri for not getting any credit. Notice Sonny, a captain or boss, for all intents and purposes, kills a guy in broad daylight. This probably wouldn't happen in real life. It's to personalize the story. It's not mob life...it's a movie about mob life. It's a movie first. There's just some tropes that make a movie or tv show timeless that might make it a bit unrealistic. If the characters are believable in their looks, behavior, accents, then stretching the truth with the situations they're involved in just tends to work.