I think types of music occur when there are some mental differences between musicians. To give an example, for jazz guitar players, most of them refuse the "benting" in jazz. If my memory is not deluding me, benting was seen in early blues player and then in rock n roll. That is a more slide way to pass the next higher note in the keyboard, but it sounds completely different when you bent the string or step on another. An example for drums, twin pedal is mostly used by metal band drummers, but whoever needs the same action in their music, bands such as Led Zeppelin, or Aerosmith, refused to have twin pedals for some reason. When we go in advance, we see many details that important musicians create come conflicts between each other. One say that is the proper way to do it, the other is completely disagree. Once you search about Ritchie Blackmore, for what kind of skills placed him as one of the very important guitarist of all times, you wil see that he was very unique about not repeating himself neither in solos or riffs, his arpeggios were always so unique and nothing usual especially at time when he played for Deep Purple. Now this could be an evidence for a fan to give him the highest level of respect, on the other hand, this could make no sense at all for another one who has different musical taste. Whoever is a fan of electronic music, especially minimal music, is always expecting the repeats. When we say music is a universal language, there are much situations to correct the idea. That is how people have different thoughts which came up with different combinations, ideas and techniques. Eric Clapton mentioned in past that one of the biggest desire of his life to make his audience cry with only one note. That is so similar what John Cage did. He was giving a concert in Germany, and people were all came over to watch him play his piano. But he just played a note, and then leave. He is the student of Arnold Schonberg, who is the father of atonal music. Even though Clapton's and Cage 's music styles are completely different, they were caught by a same desire. That is what makes it universal also. And that is exactly why people looking for sincerity when they are a fan of a band. That is why, when a band member or an artist, just start doing something new, it is a lot of excitement for someone, when another start hating her or him. That is what happen to Gwen Stefani when she left No doubt to make herself a solo album