There have been so many others exposed since I posted this, Roger Ailes, Harvey Weinstein, Bill O'Reilly, Eric Bolling, Charlie Rose, and ultimately Harvey Weinstein. Among others.
Not just Amanda Bynes, but it seems to be a whole field of producers preying on adolescent/young teen girls, extorting sex in exchange for career opportunities with their own spin-off series.
Maybe it went uncovered simply because it's just too creepy to even contemplate.