Cancel culture is not something unique to SJW's on Tumblr or Twitter. It has been around since the internet existed. When you have a communication system that anyone around the world can easily access, it becomes no longer necessary to reason with individuals who've lost trust with a community. Also, the increasingly high-speed nature of the internet encourages people to react and resolve issues quickly, encouraging people to throw out outcasts than to waste anymore time with them. You can find cancel culture in any online community. It's a consequence of being a social animal.