I don't know, but somehow I see hacking much less of a problem than harassment. I mean even the bad guys out there, trying to get into our ssh ports even minute we speak, are just a reminder to secure our systems properly. Harassment on the other side is a social phenomenon not limited to the digital world which has no upside that would be proportional to its downsides.
> problematic system design such as business models that reward clickbait
This is a real problem. I mean, it's not just about the clickbait titles. It is about an advertisement. So what is advertising? In its essence, you present information to change the inner state of a human being towards a specific direction (e.g. my product is cool, buy it!). So what an advertiser does is to forge information sources. With books, it is not much different, but with the personalized advertisement, the effectiveness has increased dramatically. Nowadays, we have effective human manipulation machines which manipulate millions of humans every day or in other words, someone has managed to crack democracy...
> unintended consequences, such as aggressive or polarised discussions
Similar to harassment, I don't think the internet is the cause here, but merely the filter to bring those nasty elements of human nature out of the dark corners of our societies. After all, people quarrel/fight/kill offline too. We probably just have to learn as a species to not be afraid our own disadvantage but to embrace diversity and make the most of combined forces instead of trying to be just a bit better than our neighbor.