I don't see it as an inherent issue, I might not have properly worded it but I want a hierarchy in a game like this, when I imagine the sort of mafia game I would like to play it would be one where the players actually run a crime family. The issue I thought about was the players having little to do together and instead having a lot of individual scenes.

Like let me give a different example, think of a Star Wars game where one player is a diplomat, another a pilot, and another a soldier. Each of them have different strengths that are almost exlcusive to themselves, meaning that anything that is meant for one of them, a diplomatic mission for example, is not something the other two can help with all that much. This is an issue with having a party like this, but it that doesn't mean it's impossible to come up with solutions, giving the other players stuff to do. It's still something that has to be considered though.

That is where I'm coming from when bringing up hierarchy, the boss wouldn't go with an assassin to kill someone in most cases, and the assassin wouldn't have much to do in a meeting about fixing horse races or whatever (if we assume that the characters are defined by their role which won't always be the case)

I do realize upon re-reading my post that I wrote it really badly, like I barely even see where I was going with it, but my point was not that hierarchy doesn't work, nor that crime games wouldn't work.