I think people have a right to know the world’s ugly, harsh facts and crazy opinions. Not knowing something doesn’t mean it doesn’t exist.
I think the solution is to remind them of all the good facts and reasonable opinions. Warn about particularly bad stuff like gore (and do block this content from children until they reach young adulthood). And most importantly, teach them how to better manage their thoughts and emotions (techniques from therapy), so they can learn about bad stuff without being hurt or biased from it.
Then again, this take is from my own ignorance and personality. Maybe I haven’t been exposed to the real ugly stuff, or maybe I’m better at not reacting to stuff emotionally than others. But the main issue with restricting harsh information is, not knowing something doesn’t mean it doesn’t exist.