> How is that different than working for the Gambinos?

The Gambino crime family is actually an organization or group in the traditional sense. "Anonymous" is more analogous to "The Mafia". A useful term if you are okay with being imprecise, but the reality of "The Mafia" is encompasses a very broad set of groups that more often than not have absolutely nothing to do with each other.

Of course there are a few differences between the concept of "Anonymous" and the concept of "The Mafia". Groups that identify as "The Mafia" have more in common with each other than groups who identify as "Anonymous" (the former are all organized crime groups, the later can be any group from organized crime groups, to people who wear silly masks and protest fringe religions, to people who call the parents of kids who abuse cats and post pictures to facebook.) Furthermore, if I burn down a local business and then claim to be The Mafia, mainstream media would mock me for delusionally thinking I had any claim to the term. If I defaced a local businesses website and then claimed to be "Anonymous", the media would lap that bullshit up.

A lot of people would argue that it shouldnt happen in the case of the gambinos either and that RICO is an overreach

And I'd be one of those people. But you can't run around telling everyone you're a member of a shadowy criminal organization named Anonymous and not expect people to treat you like, you know, a member of a shadowy criminal organization named Anonymous.

it's the same distinction as setting up a shop selling pirated movies with fake dvd boxes vs using piratebay ocassionaly.