To a person who lacks self-control, many commonplace things become dangerous. Children are notorious for lacking self-control, especially emotional self-control, and are generally more susceptible to suggestion than mature adults. When my kids were growing up, my wife and I paid a lot of attention to their environment to mitigate the kinds of negative influences they weren't prepared to handle alone. I never tried to pawn off my responsibility as a parent to questionable Internet companies, school boards, the government, or anyone else. At times I failed, but even that did not deter me from my duty to my children.
My kids are grown now, mentally healthy, and it gives me a wonderful sense of accomplishment to know I managed to navigate the minefield of childhood development with them. As you might imagine, I cannot fathom a situation where I would neglect my child enough to turn them loose on social media without taking strict precautions. Most of the time I didn't have to bother protecting them directly from bullying, peer pressure, or other social negatives. Rather, I tended to let normal life happen and taught them the coping skills they needed to deal with the issues as they arose. But - only to the point that they would be effectively able to handle them at their current maturity level.
My kids never liked or pinned or whatever 10k+ social posts glorifying suicide. That's way beyond the pale, and I would have stepped in long before that to help them deal with their issues if I could or to obtain specialized help otherwise. Requiring social media companies to clean up their act is needful, but parents need look no further than themselves for the responsibility of failing to facilitate their child's development to this degree.