I don't think anyone is seriously demonizing sex here, but there is a question of whether or not teenagers are aware of the consequences of their actions and whether or not they're capable of making proper decisions.

No parent wants to see their child get sick or pregnant as a result of a rash decision. This is simply an issue of emotional maturity.

As someone who graduated from high school and attended college recently, I can safely say most of the people I knew in high school weren't ready to have sex. They were simply still children in mature bodies.

By college, some of them had grown up a little, but the majority were still acting childish, never having had responsibility for anything. The way we raise children in this society prolongs their dependence on their parents and makes it hard for them to learn responsibility. As long as this remains the case, most teenagers won't be ready to have sex.

They'll engage in sex because of social pressure, or out of curiosity, or because their parents never properly educated them. Some will come out fine, while others will be emotionally or physically injured. Too many will fail to use birth control or use it incorrectly.