The idea that 4chan doesn't have moderation isn't true. I largely have to suspect it has to do with the the time moot stopped making bans public, but 4chan moderation used to be very visible. A number of other alternate chans were created because 4chan was "too strict". Even /pol/'s current political flavor is a product of deliberate moderation. Regardless, despite 4chan's "lack of moderation", with the exception of /pol/, the level of racism and hate you see isn't anywhere near what you would see on voat.