Think about it like this: When information advantage, research advantage and speed provides edge, why would anything that is openly available to everybody hand out free money?
Obviously, there is no free money.
I'll counter this argument with asking you why not every student in school is a top student? After all - the resources are equally available to everyone?
Just because everyone have access to the same information does not mean they process / utilize it the same way.
I bet it's common in trading firms too that certain traders outperform the rest - even if they have the same resources at hand.