There is an insight piece by Justin Murphy, http://jmrphy.net/blog/2017/05/15/psychology-of-prohibiting-outside-thinkers/, which deals, from the perspective of the Left, with the Left-wing dominance of the culture of discourse in the West.
Why does the Left close down Right wing thought, on moral grounds? Actually he should have probed deeper and recognised that the Left openly resort to violence to shut down anyone they see as a threat. On university campuses, even notices challenging aspects of globalisation get torn down. Therefore, the article is somewhat superficial and does not address the clear fact that the Left has state-legitimated terrorists who freely break the law, and are permitted to get away with it. These terrorists within a few years move into positions of power and continue the agenda of national suicide and racial destruction.
Still, for its limits, the article has some merits, although written in the usual academic language: