I can't see why opposing thoughts should be so problematic, yet it seems it was ever the case. Thrust and riposte are fundamental to not living in a reciprocating, back-slapping, echo-chamber. The whole point of not agreeing with everyone else is that alternative views can be espoused, taken on board and argued for or against. That's why open debate is so important. Anyone who frequented student unions in the 1970s will be fully aware of the way any dissenting ideas were shouted down by the left. I suspect nothing has changed given the tendency for youth to be left of centre.