Ironic, given that there a lot of artwork of cats and dogs here such this post #2858709 and this post #2977865
Ah, the classic "we allow other posts of this type, so this one is fine too!" argument. As the usual rejoinder goes, if you find images in the gallery that you believe break the rules, flag them. Though you might have a bit of trouble making the case that Matataku's art is off-topic, given that he draws a lot of actual anime-style art.