Here's why:
-Promotes pedophilia
-Promotes homosexuality
-Promotes cross-dressing and transgenderism
-Promotes lust/coomerism
-It is emasculating; It markets girly/cutesy shit to men, degrading their masculinity in the process. If you are a grown man listening to an underage girl with a high-pitched voice singing about cutesy shit, you need to re-evaluate your life.
-Gets men attracted to cartoon women, diverting their focus from attaining relationships with real women in the process. If we want to rebuild the white family and raise white birthrates, banning anime will help.
-Non-Western; Whites should stick to Western media media as much as possible in order to preserve their culture.

Now what about the common counter-arguments?
>But Hollywood is bad!
First of all, Thing A being bad doesn't automatically make Thing B good. Secondly, you can find non-degenerate Western media if you're willing to look for it.
>But this is an anime site!
It may have been when it was first founded, but the scope of this site has long since expanded beyond it. Most boards, including this one, are not focused on anime.
>But anime promotes muh based redpilled trad values!
Maybe a handful, but most don't. Even if an anime series shows traditional gender roles, the quality of the series is usually offset by pedophilia, emasculation, and/or coomer shit.
>But no black people!
Not many white people either. Most anime characters are Asian.