Reddit is among the most widely-used websites in the world -- 7th, by Alexa's rankings. Reddit lives up to its motto of being the front page of the internet.
Imagine one of the top-10 newspapers in the United States were occasionally publishing stuff from /r/The_Donald on its front page, and had content from various hateful sub-reddits a few pages back. You could argue that this imaginary publication harms society.
Of course, Reddit is not the New York Times. So different standards apply. But the argument that Reddit -- and thus its administrators policies -- may be harming society, seems to hold some weight.