Maintaining accountability ...
Yes, everyone was accountable to some supposed higher level - branch, limb, etc - but the BoT (as it was when I was around), or BoD nowadays, didn't consider itself accountabe to anyone or anything. They accounted for none of their actions, for none of the consequences of any words or "doctrine," and not for the money given to them in trust.
I love that churches I know of here have a proper structure and no one is left unaccountable. That also means that leaders, vicars, etc, aren't left feeling either Godlike in power, nor, conversely, unsupported by those they serve. There's a lot to be said for accountability and orderliness.