Just my opinion (which probably doesn't mean much)...
This is a culture fostered not just by USAG, but also by every coach in the sport. How many times I've had conversations with coaches and parents about the state of elite gymnastics in the US only to be told that if a gymnast can't be competitive at the elite level by the time they're 13, they're too old. THIS IS WHAT CREATED THE ENVIRONMENT FOR SOMEONE LIKE NASSAR! Young children, boys and girls, CANNOT advocate for themselves--they simply lack the maturity to do so. They still believe all adults are concerned with their well-being and will only act in their best interest. Thus, if something happens to them that makes them uncomfortable or that their gut tells them is wrong, they CANNOT speak up because it doesn't make sense to them. Children don't gain this ability until they enter the teenage years, but by then, according to the way you create elites in this country, they've already been groomed to believe that speaking up--even when they know they have to--is the wrong thing to do.
I've seen it at DD's gym--parents of a young girl walk in and, after a few rec classes, are told their daughter is good enough for team. Yes, of course she's good enough for team. Don't we all know our progeny are superstars? After a bit of time on team, they're told their daughter is the right age and has the right body type to be an elite, and the coach would like to start TOPS training with her. The parents are told this is a special class only available to those who are the most talented. So, with stars in their eyes and Olympic dreams in their minds, the parents blindly follow along. As the child grows up, she comes to believe that telling her coach (who has so much faith in her ability) and her parents (who have invested so much time and money into her training) that something is not right is wrong. So she stays quiet. She'll go on to attend camps where she'll meet other girls who have similar stories. They commiserate with one another, but their reality is that here is nothing they can do without disappointing the whole (gymnastics) world. So they continue to suffer in silence, drawing strength from the bond their secret has forged.
It is so very difficult to speak out about sexual abuse in this country. When you feel like you have the weight of the entire country on your shoulders, it becomes that much more difficult. Until this belief system is replaced, the only thing that will change are the names and faces running the show.