None of those sites allow anything whats is "socially unacceptable" they are very afraid of controversy or insulting someone's feelings.

You can survive if nobody complains or notices but even if you will use word "nigger" in your manga you will likely get banned.

this is even the case with lolis on pixiv where it is generally fine to do normal porn but if you will post some rape or disturbing scenes you may get suspended. because in japan children being fucked is ok but not ok if they are put into meat grinder