When I was growing up, it was perfectly normal for adolescent boys to be curious and look at magazines like Playboy when the opportunity arose. The fact that we did this doesn't make it right, but it was the norm.
Today, however, children have instant and unfettered access to pornography on the internet and it is far more graphic than anything that existed in magazines a few decades ago. Additionally, girls are viewing it (if they looked at pornography in my day it was certainly a secret) and using what they see as the basis for how they should look (piercings, shaving pubic areas, etc.) and this is done without any realization that all of the women they see are Photoshopped (in the 60s, 70s and 80s photographers were able to "touch up" blemishes and make-up was used, but the women looked how they really looked). The net result is that young people today believe that what they see in pornography as the norm.
The whole "hook-up" culture is largely a byproduct of pornography because boys AND girls are viewing porn as normal. When I was in high school in the 80s, girls who were promiscuous were considered sluts, but their behavior today wouldn't even be out of the ordinary. Thirty years ago the girls who were called sluts didn't like it (and in some cases hadn't actually done what they were rumored to have done), but it kept the other girls from emulating them.
Exactly.