I guess it depends on the IFE system but in new ones you can restrict individual IFE channels to the entire cabin or even individual seats, including the flight path. Our Panasonic system allows channels to be blocked at individual seats, and when there are unaccompanied minors travelling, we are supposed to restrict access of any program above a G rating to that seat.
Sometimes it is a worthwhile feature. Example, LAX to MEL with a lengthy delay to takeoff. Initial planned flight time would have crew just scraping in within their duty limitation. Lots of diverting around weather in the first 5 or 6 hours of the flight and stronger than forecast headwinds meant 7 hours before landing in Melbourne decision to divert to SYD was made and flight plan adjusted. Announcements not made as it was middle of the night and everyone was asleep but as they started to wake and check the flight path to see how long to go, surprise, the little dotted line to destination points to Sydney. Next 2 hours spent explaining individually why we were going to Sydney, no I'm not sure about your connection, etc, etc.