You are suddenly shaken awake from your restless, fractured sleep. A woman with a look of bright concern implores "Sir your son is watching porn!" "Huh?" She gestures to your right towards the 11 year old boy seated there. "That's not my son"
Remember, children as young as five can fly with out a parent/guardian (in the US, per AA website). So that could happen without change to regulations.
Is that a meaningful distinction, though? "Aware of" != "Actively supervising". I guess it's easier to page a flight attendant than find a parent seated elsewhere, but neither can provide active supervision.
This presumably would mean you’d be feeding a random kid a bottle on long flights. God knows how they’d accommodate breastfeeding.