Music theory can get pretty wild, yeah. The main difference to me when comparing it to (for example) physics theory is that it's usually an aesthetic pursuit. As in, studying physics has the end goal of understanding how the universe works, but theorizing about music involves the aesthetic value of the sound -- why and how something "works" (or doesn't), what feelings or emotions are evoked by certain types of sound, and how to apply this to composing new music, or understanding existing music.
