Alternatively, children having reach and access to bully other children at any time and any place (more specifically, in their own home) is only made possible through technology. Social media absolutely deserves attention.
Also: I was bullied as a child and I suspect this is a claim most adults of any generation can make.
People are much more likely to say mean things to another when they're behind a keyboard and talking to a screen name or avatar. And real life conversations are much harder to manipulate as compared to social media. Add to that that these platforms monetize by keeping your attention, so there is an addictive component to them. Quitting social media is often very hard, psychologically.
You're correct that many of the problems with social media are not unique to the technology, but like a lot of technology it often times makes existing problems worse. There are strong correlations between certain kinds of social media content and the development of eating disorders and self harm, especially among young people. And we have the ability to start mitigating those problems today, but "fixing" human behavior is going to take a little longer.