The history of speech therapy is actually pretty interesting. Part of me is surprised people even cared about speech therapy in the "olden days" but at the same time it kinda makes sense especially considering how much we still judge others based on their dialects and idiolects. While reading about theories of phonology, I almost think of it as a progression of common sense. Distinctive features theory seems so complex and specific but is still very limited. I would never be able to think of all the intricate details the distinguish one sound from another. But it does seem rather odd that it took such brilliant minds so long to recognize that speech is more than just the sounds that come out. Even children can recognize the complexities of speech but we rarely ever acknowledge those complexities. I'm sure that within the next fifty years there will be some new cutting-edge theory identifying another dimension of speech that will seem like "common sense" once it's discovered.