No, I'm not saying self-identification is a universal standard adopted for categories. But I think with broad issues of where a religion is categorized, we kind of do. In any case, most neutral academic sources place the Latter Day Saint movement within the Restorationism branch of Christianity, so I don't think we even really need to rely on self-identification in this case anyway, because there's not really a conflict between where the group self-identifies and where academics place it in the broad context.