Leaving violence aside as that's not the subject of the thread, how do you define porn? If it's naked or partially clothed bodies, then I guess it is "everywhere", but seriously what's wrong with that? I'd call porn explicit representation of sexual activity. You don't see that in supermarkets, at least I don't.
We've come out of the "Victorian" age where people covered up the "legs" of tables in case someone was offended. Back when I grew up in the 1940s and 50s, and the sex education I received in school and at home was none, nothing, zero. Can't talk about that, it's "dirty". Slight correction, often inaccurate information was passed around in the playground. Do you really want to go back to that?
In my lifetime since then I've seen the depiction of sex become more and more permissive. Somehow though the old puritanism still lurks under the surface, as we see in this thread, with discussions of whether "porn" is harmful. Of course it is, after all sex is dirty, surely you see that, it all happens "down there" and that's a kind of not nice place. It's a natural physical activity folks! It can only be harmful if it involves things that actually do harm, and pretty much all of those things exist are not inherent to sexual activities but go on in lots of other activities.