I think it would be true. If the League is above the law, then the only law is the law of the jungle. The law of the jungle is enforced by the strongest, like an organized crime group. The ranking may or may not be official, but it all comes down to 'what are you going to do about it?' Eventually the individuals or groups of individuals who have the power to 'do something about it' when people cross them are the ones who get their way.
Edit:
An equilibrium would eventually form as the strongest groups reach a consensus in which each of them is getting an acceptable cut of whatever they want. The consensus holds as long as the balance of power holds.
Weaker individuals would become followers or supporters of stronger individuals. Weaker individuals could also band together for strength in numbers or to have a 'seat at the table' so to speak. Stronger groups might do what it takes to prevent such groups from forming or being successful.
Another Edit:
Socially, i think there would be an unofficial ranking system in which more powerful supers would be respected more than weaker supers. Think of it this way. In a mixed martial arts league, a fighter might be able to beat anyone not in the league, but most of the fighters good enough to be in the league can kick his ass. Nobody would respect him, nobody would listen to him, he would become the target of abuse, because there wouldn't be anything he could do about it. A stronger super could kick sand in his face at the beach and there would be nothing he could do about it, because if he pushes the issue, he'll get his ass kicked. He knows it and everybody knows it.
There would be a social spectrum, with the weakest on one end and the strongest on the other. Weaker supers wouldn't be 'the cool kids' or the 'jet set'. Other supers wouldn't want to hang out with them or be seen with them. They wouldn't get invited to parties or get high profile missions. They wouldn't get corporate endorsements or comic lines made about them. When they are noticed it's probably not for very long, and they get treated like 'the help'.