I think it goes back to the 60's and even earlier. It comes from a number of things but the final drivers are greed and power. Way back the excuse was often "If I don't do it, who will?". Today it's "Look at me! Look at me! Damn I'm Good!" You can see that in these forums.
The majority of the membership uses the AMA simply for the insurance and/or access to the local club field. Nothing more. (Interestingly the actual need for this is fast disappearing.) And they couldn't care less about AMA politics or business so they ignore the whole thing. This enables the GOBs at the local levels to basically take over and establish a "My way or the Hi Way" environments. Not unlike what you see in many forums and the way the mods moderate. And this goes all the way back to Muncie.
So Egos have taken over and the GOBs are making the AMA into their own image vice what it should be. And the GOBs are using the AMA to their own benefit and not the memberships. And it all comes back to the desires of greed and power.
On an aside, there are some interesting 1st Amendment discussions out there about Mods and forums.