I had wanted to talk about this, but it was a little off topic in the thread that it was in. In the interest of perserving a topic, here is the issue that came up.
I think that there are a lot of sub reasons - yes, I agree- but what's the real reason? To me, it's jurisdiction. Jurisdiction is the range of your authority. Standards are an expression of your authority. Once you have jurisdiction, then you express your authority in all sorts of ways. You make the internal rules once it is determined that you're the boss over a certain territory. Organizationally, then you protect your organizational "life" by guarding the perimeters of your territory. There is seeping incursions into your territory but you identify those and either "regularize" them into your group or you segregate them.
Organizations sell themselves by advertising higher standards, a better truer style, masters that were closer to the founder or understood his Aikido better, etc. Haven't you ever noticed how many "last" uchi deshi's there are or how the organizations say that their shihan was a favorite of the Founder. These are advertising methods that are intended to convince the followers that they are in the best group and that their group is superior. This is an ego enhancing method. Organizations must distinguish themselves from the others somehow. They drive toward distinctions. Distinctions keep them apart. They want to be apart because if they are all together, then jurisdiction disappears. Distinctions like "better standards" are an advertisement used to convince the followers to stay within the jurisdiction.