I think it's monetisation. In the past, monetising your opinion was difficult. It was limited to a select few who could get on the TV or in the print media. Now, people are incentivised to say things which will generate controversy because eyeballs == money. If you got on Twitter and started posting polarising opinions and worked on promoting those eventually the engagement will (possibly) reach a point where you can gain financially from it and you're now incentivised to continue posting polarising content. The content doesn't even need to be ethically right/wrong, it just needs to make one group of people angry and another defensive. There are plenty of things we need to have a debate about as a society (because they are not black/white and require nuance to solve) but they will never get solved properly because both sides refuse to discuss the issue.