It's not what Danbooru was created for in any way, shape, or form. Art by Japanese, by Westerners or whomever of Japanese IPs, or classical Japanese art, that's all fine. I'd even extend to obvious cases of classic impressionism or otherwise that fall under Japonism. But Bouguereau is so far outside Danbooru's scope that I'm not sure why they're allowed no matter how good they are.