Because r34 is filled with pedos, zoophiles, SHITTED/"BNWO" obsessed fags, cucks, and degens. The mods and jannies are a bunch of trannies so they'll be okay with degen things like i said earlier yet despise WMXF because "white man bad" and general anti-whiteness.
Let's not forget they are on the same level as 4chan jannies: They will allow pedoshit/child gore, zoophilia, anti-white racism (which is ironic because muh no raysism rule yet anti-white racism is okay but god forbid anon says a mean joke to other ethnic groups), spam, low quality content, and a bunch of degenracy yet white cock good is too far for these morons.
Anyone who wants to find WMXF/bleached aren't going to find any there because r34 mods hate it so it's just best to stay at bleachbooru because I think it's the only known bleached site i found (dunno about more but i remember there was an old bleachedbooru recently) and has quality control unlike other sites.