What I from the left has similarities to the religious fervor of my youth. You either believe and are part of the solution. To do that you have to convert everyone, and if you aren't with us then you're against us. It might be that it just evokes a similar emotional response to me as being on the "outs" with my childhood faith.
Many people want to have faith in something. We've torn down religion as fairly corrupt, government has been likewise torn down for many people. Now we have massive leaderless movements that offer the same sort of thing.
My issue with this movement, is it's amplified the worst of our human nature by having social media (which I recognize I'm consuming right now). If you don't want global censoring of opposing ideas we need to have a better way of performing human interactions online. We need more humanization of people through technology not the dehumanization of people through technology.