Why do people constantly bring up pedophilia when it concerns 16-17 year olds? Let's not dilute the meaning of the term.
A guy who's into 7 year old kids is not the same as a guy who's into a 17 year old late teenager. The latter might be an asshole, with morally questionable tendencies, but the former is a monster. It doesn't do anybody any favours, to act as if the two scenarios are the same.
The reason we've come to treat 18 as the golden number (although 16 is still the age of consent in much of the world), is because of relatively recent scientific findings regarding the general physical, psychological and emotional development of teenagers. Some people develop faster, some later, but at 18, we can be quite certain that an individual is capable enough of handling their own affairs.