And the point that is being made is that the Imperium is not an analog of Medieval Fiefdoms.
Not an analog, no. But the point of scale remains. The way it is presented is one Barony per planet, where there should be many, and someone with sway over a whole planet (even if it is just interstellar trade and relations to the greater polity) should be much higher in rank.
Suppose the Imperium were instead a Federation with a constitutional-republican form of government. How would it govern itself? It would appoint administrators, bureaucrats, and functionaries at various levels of interstellar federal government to control its ministries and institutions, just like any modern government does for its own national ministries.
A Federation, by definition, means an agreement between parties or a binding of parties. They act together for the purposes of the Federation, but retain their own authority or autonomy. You are describing something of a different nature (I won't veer off into current events). But such a government would have no authority to appoint nobles to control anything. Member polities would send representatives to the Federal, not the other way around.
The scope would be larger and require more levels, but since this Interstellar Federation is not directly ruling its worlds, but mostly governing its federal-level interplanetary commerce, and collecting tax revenues to support armed forces at a larger (federal) interstellar scale, it does not need to provide granular administrative oversight of local planetary affairs, budgets, economies, and armed forces (which are analogs to U.S. States, U.S. State Militias and/or U.S. State National Guard forces). Interstellar government (including Federal interstellar trade regulators and Federal military organization beginning at the Subsector level as Interstellar Military Active and Reserve Forces) does not need functionaries that scale down to the sub-planetary level.
The analog to the antebellum era and the ACW is apt. The Federal Army was not a permanent body, but more a skeleton crew and an officer training corps. States were responsible for raising military units which would be submitted to the Federal Army when called up. While direct warfare with a foreign state would call on Federal assets to venture outside the borders, local defense against uprisings and barbarians should be handled by militia. Instead, States abdicated the expense of maintaining a decent strength of militia. When trouble came they called on the Federal Army to intervene, going all the way back to the Whiskey Rebellion. An exception to this would be Texas using Rangers and militia to fight against Mexican cattle gangs and the like.
In a milieu wherein the nearest Naval force might be weeks away under average circumstances and months away if engaged in some defense deemed more important, it would be up to the local government(s) to maintain local defense at a strength sufficient to repel any minor incursions or raids.
The Imperium functions the same way, it is just that its higher-level interstellar "administrators and bureaucrats" are a subset of individuals chosen exclusively from an "old-boys" network of individuals and/or families who have otherwise been granted Noble titles and land grants for self-support and upkeep by a current or prior Emperor as a sinecure.
- An Imperially-assigned Landed Knight is an Imperial ambassador to the world that represents the Imperium and its interests to the local government and people, and advises accordingly. His fief is merely provided for prestige and his own personal upkeep thru a portion of local Imperial tax-revenue.
- An Imperially-assigned Landed Noble is a representative for the world to the other worlds of the Imperium (thru their own Landed Nobles) at the local Subsector Moot at the Subsector Duke's court, and to the Imperium as a whole at the Imperial Moot on Capital (either personally or by proxy thru a chosen representative).
- Imperial "Gentlebeings" or "Gentlesophonts" (Soc=10) would be the general run-of-the-mill operatives of the various Imperial Ministries and Bureaucracies who operate at the Interplanetary level.
- An Imperial Ceremonial Knight or Ceremonial Noble is an Imperial administrator overseeing some aspect of the Imperial Subsector governing structure at some level as a Director, Deputy-director, or lower level departmental-supervisor of the various Imperial Ministries and Bureaucracies.
All other Imperial Nobles (i.e.
Honor Nobles) are simply part of the upper-crust network (great or small) of Imperial elites who happen to have remunerative land grants assigned by the Emperor (at his pleasure) and/or personal assets, but otherwise have either no function, or merely minor ceremonial function (though they may be maneuvering to get a more prestigious formal posting of some sort for themselves, based on their own personal ambitions).
Except if the Imperium doesn't rule locally, how does it have authority to grant fiefdoms locally? You can only grant from what you rule or possess. How does an externally appointed noble, with no organic connection to the local governance/populace, represent that government or populace in a higher polity?
In the USA, the Federal government can't appoint anybody at the state level. There are Federal courts, with Federal judges seated, but only to handle Federal issues. A Territory has Federal appointees for governance and law enforcement, but not a constituent State. What does the Imperium administer that it appoints administrators and happens to have control over local lands to hand out as fiefdoms for those appointed?
How many Bureaus does this Imperium-that-doesn't-rule need? A Department of Defense equivalent, a Bureau of Investigation equivalent, an Intelligence Agency, and a State Department equivalent. The Imps wouldn't do any equivalent to domestic bureaus (education, health, housing, transportation, etc). Yes, some sort of Interplanetary Trade oversight to handle disputes between or involving member world interactions.
I would argue that you don't actually want nobles entrenched into any of these Bureaus. That would be inviting all kinds of trouble, lucky to last a whole century without a coup of some sort. State would be small in the OTU. There are only half a dozen outside polities significant enough to require formal external relations. Yes, there would probably be some sinecures in Trade.
The Medieval Fiefdom is a straw-man argument. The Imperium is not an analog of Medieval Feudalism, so showing how the OTU as otherwise described could not work as a network of Medieval Fiefdoms is simply disproving a case that nobody else is making.
I didn't argue that the Imperium was Feudal. I was only looking at the size of noble holdings and what benefit the Imp gets from having appointed offices of that sort.