Otakus are users on iFunny who like anime. This wouldn't be a problem except they usually post pictures and screenshots from anime which aren't necessarily funny. Other posts can be funny but to enjoy the humour you have to be a fan of anime which ultimately makes all of the otakus community posts exclusive to other otakus.
For the above reasons, the controversy with otaku's is that their posts are for an exclusive audience making it annoying for other users who are too lazy to just ignore their posts.
Massive ban raids in the previous years were directed to otakus but now, on iFunny, almost every other post in collective is an anime related picture.