Its not Rapid Onset Gender Disphoria. It just means the parents didn't know their kids had these feelings for a while, were clueless, and when they were told think it must have been "sudden" and want something to blame. So they blame ROGD and the friends their kids hang out with, instead of accepting their children for who they are.
Here is the thing, while parents may not pay attention to their kids, kids are paying attention to their parents. If a parent says transphobic things, they know who their parents are listening to. A kid is not going to come out to that parent. They will however look for people their age in similar situations.
People like Dr. Peterson is why kids are afraid to tell their parents these things.