Mods exist and can ban/lock/block people and content but users can see everything that was banned, removed or locked, as well as the reason why; what policy did the user violate?
I think the only exception would be actually illegal content; that should be removed entirely, but maybe keep a note from the mods in its place stating "illegal content".
That way users can actually scrutinise what the mods do and one doesn't wonder whether or not the mods removed a post because they are biased or for ligit reasons, and opinions are not entirely removed, as they are still readable, but you can't respond to them