Of course it's normal to masturbate, humans as animals are always going to feel natural sexual urges. The problem is when sexually frustrated teenagers are going to these sites and being exposed to videos that brutalize women and stereotype gay men, not to mention pseudo-incest, pedophilic "barely legal", and raceplay tropes that make up most of mainstream porn, even that of which is made by amateurs with a good quality camera. I have seen firsthand the trauma this shit causes and how the overconsumption of it leads people to hurt other people, even within their own families, because they saw some "oh no, what are you doing stepbro!" vids one too many times and took it upon themselves to try it on someone close to them.