In older times, teenagers (above say, 14) were considered men, or young adults. They would fight in armies, or even lead them. They were likely to be married and maybe even have children.
For all intents and purposes, people of age 16 are not much different from other adults except in that they don't have much experience in life. The only reason they "rebel" is that society still treats them like children. Imagine a 30 year old man being treated as a little hopeless child by his parents; of course he will show signs of resentment. It's not because he's "crazy", it's the natural response.
Perhaps the reason is partly due to school. If you're in school (below university/college level) you're a child "by definition" so to speak (from the society's point of view).
If I was in charge, I would design the school system so that elementary and secondary school end by the age 14 and then when you're 15 you'd be already in college.