Why, because it hurts their feelings? To protect them from the consequences of what they said, and ensure everyone has a chance to hear it? Downvoting is an exercise of free speech, too, you know.
https://en.wikipedia.org/wiki/Controversial_Reddit_communiti...
for starters always check eye contact with driver of big truck in front of you plan to cross the road
i think i was already before shielding myself behind poles at junctions
But then that is just one objective analyze of the subs. It would be interesting to know what kind of definitive standard tool we could use in order to define which subs should be banned.
Looking at the Wikipedia article, their definition is that a sub is controversial if a reliable source (primarily a news paper) call a sub controversial, and such it list one feminist sub and one mens rights sub. It not the best definition of truth, as people in the education system and research community commonly points out, but as an approximation it gives the outline of the issue.