Online abuse is out of control?

There is a recent TED talk about how the online abuse of women has "spiralled out of control". I have great sympathy for anyone who has experienced online abuse, but there is no mystery as to why this abuse occurs and how to deal with it. Abuse occurs because there are extremely vile people online, and current social media gives these people almost unlimited access to abuse anyone. 

We realised the problem of abuse decades ago in the early 90s when the Internet changed from being used mainly by academics to accessible by the general public. To deal with this change social forums like usenet were set up with moderation. This worked pretty well. What went wrong was that new social media were launched with no barriers to entry and, by default, everyone being accessible by everyone else. 

The idea that such wide open systems would be free from bullying and harassment was hopelessly naive. Instead of using online abuse as evidence of how broken our societies are, campaigners should insist that the terrible design flaws in social media such as Twitter and Facebook are fixed.