As a parent of 3 girls and 1 boy who have all passed that stage, I can say that I agree with that statement. I think when I was a teenager, back in the '70s, is when the shift started to happen. I have no idea why it happened.
I will say this, you're point bolsters mine. Women in the 20's (especially early 20's) having relations with 16/17 year-old men is NOT pedophilia. We would prefer that teenagers abstain from all sexual contact, at least if they're not married. But, let's face it, some are going to be sexually active. 10 year-olds, should NEVER EVER be engaging in any kind of sexual or even intimate behavior. There' the difference.
Pedophilia is the predation of children. 16 and 17 year-olds are not children and certainly weren't when this country was founded and for the next 150 or so years. But, there been some kind of push, and I believe it's come from the leftist of this country, to coddle and infantilize teenagers when we should be treating them more like adults.
It really started to bug me, when at the start of the Iraq/Afghanistan war, we saw groups like "Code Pink" describe these 17/18/19 year-old men as "sending our children" off to war. 17/18/19 men are the people who won the second World War, and every other war that America has fought. We shouldn't forget it.
Hand in hand with the coddling of teenagers is the extension of adolescence well into our 20s and 30s. I think this mindset really took hold with the raising of the drinking age to 21.
Jack Daniel became a licensed distiller at 16 but today, childhood seems to last forever.