Knowing all the allegations that surface against people these days, it's pretty chilling to think about all the stuff like this that was just swept under the rug or condoned for centuries.
From talking with various in-laws who grew up in middle-upper class East coast families, there was some very sketchy stuff happening before the 60s, especially to women. Things like lobotomies or institutionalizations, just to get an undesirable person out of the way.
The prosecution successfully argued against the 'defense of infancy' based on things the kids said themselves admitted they had planned to do to the victim.
They don't have full capabilities yet. Their ability to plan is lower and their impulse control too. There is not way for them to enact years long plan and build networks of supporters before acting.
I'd wager that the vast majority of bad behaviour is still swept under the rug and/or condoned. Just because there has been a few visible cases doesn't mean we're eliminating the problem.