Porn shapes society the exact moment when the majority of young people get the majority of their beliefs and views on sexuality, romance, relationships, gender roles, sensuality, etc, from porn. This isn't true of all groups of humans everywhere, but it's definitely true of many societies right now already, and I would say obviously so.
None of this is meant as a "moral panic" type point. I'm just saying, there's no point hiding from the reality that young people get their views on sex from online porn, and that has major effects on them and the whole of society.