The analogy has frequently been made to a dictatorship (vs. a democracy) -- and, barring only the willingness of the administrator to consider the wishes of others, this is precisely accurate. It is also very dangerous: for there are absolutely no direct checks on the administrator's power.
The one thing that the administrator does not directly control (the most important thing, in my book) is the willingness of others to go along with the specific expressed elements of that dictatorship. Without its members, a board is nothing. Without the willing contributions of other members, all the power of the administrator is negated.
Thus, the administrator's power rests entirely in the willingness of the board's members to accept that administrator and the manner in which power is wielded by that administrator.
Further, since the board's members are highly unlikely to remain at a board where power of this nature is exercised arbitrarily, without cause, or too freely (unless this is the specific nature of the board in question and this was initially understood and accepted by the members), the greatest power of the administrator lies, not in active and/or frequent exercise of that power, but in its potential for use. In fact, the more actively power is used, the less effective it becomes.
In many EZ-Board cases, the question of appropriate use of administrative power is very much a moot one: since many EZ-Boards are created around small, established communities rarely numbering over 100 (not including alternate names). Everybody knows everybody, the (implicit) rules are known to everybody, and those few who wander in and are not willing to abide by those implicit rules are either quietly (roughly) discouraged or banned, with the condoning of the entire community. The question of appropriateness of use of power never arises: because the administrator, too, is a part of the group, and shares its sense of appropriateness.
What happens, however: when a topic-oriented board becomes "established", perhaps having acquired several hundred members -- and the individual members, being no longer individually known, cease to have individual meaning?
At what point does the drive for power in the interests of the community become the drive for power in the interests of preserving the current power structure (and, not incidentally, one's own individual power)?