Surprisingly many characters in Unicode are only recorded a few times if not once before the assignment. Chinese characters for example have a lot of them, because it was relatively frequent to make a new character for newborns before the modernity and some of them have survived through literatures but otherwise seen no uses (e.g. 𡸫 U+21E2B only appears once in the Records of the Three Kingdoms 三國志). But they have still received code points because they are considered essential for digitaization of historical works, and multiocular O is no different.