>Most of the outside-the-overton-window discussion on 4chan is discussion of national socialism, with an occasional call for genocide.

If your impression of 4chan as a whole is just /pol/. 4chan as a whole is much more ideologically diverse than reddit due largely to the site's format and lack of censorship, but if you're an outsider to 4chan's (often outlandish and intentionally offensive) cultural norms you're just going to think it's a nazi site. Mainstream media has tried and failed to understand it for decades now.