It's nothing new or "changing", ellipsis. Certainly as long as I've been alive there have been transsexuals, generally very much accepted and respected. The problem is not "just" language though, the problem is that it's now being taken too literally and you only have to call yourself "she" for a man to break women's sports world records, be put into women's prisons and so on. You've seen lists of names and examples on here, plus the extra dangers and injuries.
Be whatever gender you like, whenever- nobody cares, but getting it confused with biological sex, is, and has been a problem. And using the wrong language seems to be a big part of that, because people genuinely believe often, that how they feel or identify, should be related to their sex. But why?