Usually I respond to a question like this with 'It's complicated.'

But I've been thinking about this question quite a bit over the years and here is my thinking at the moment. First let's clear away terminology: 'domain', 'demesne', and related terms in the period 1000-1350 were rhetorical and polemical terms which required a community to recognize to have an force. In western Europe, real 'law' as we would recognize it (not cartularies and the like) was only in development post 1150 at best. Realistically it took another 200 years to calcify through the efforts of secular and ecclesiastical chanceries, lawmakers and jurists. A domain had nothing in the 'apparatus of state' to hang on to. In so far as enforcement of a claim of 'domain' was concerned in much of this time period, it was entirely a function of community agreement, or agreement among peers - in this case nobility with monarchy. This was forced upon England far earlier than France through William the Conqueror and his immediate descendants - which is why we can see 'centralizing effects' earlier in England than France.

The 'community agreement' I mention is perhaps the idea most difficult to comprehend, but in fact it's quite simple. Nothing in the high middle ages happened without a form of community agreement, whether peers of nobility, or nobility acceding to monarchy. Case in point, the submission of Raymond VII of Toulouse under the Treaty of Paris-Meaux in 1229, which effectively ceded the south of France to the monarch of France over the course of the next 70 years. The mechanism of ceding was in several parts, but it happened because the king of France achieved a submission of Raymond. The submission was witnessed by many important members of the community, peers, who could give it force, and who gave it weight - not because it was a contract that could be fought in court. And in fact Raymond rebelled against this, as did a number of southern nobility over the next decades. The south became the king's domain; but only when he put in nobility that were loyal to him - and placed sergeants and bailiffs in positions where they could enforce the king's will - would the king be able to enforce his will (what we call, perhaps anachronistically, early state-building). But a claim to domain had little to do with the ability to place his people there.

Another example: the barons who signed onto the Magna Carta were a community which validated the claims of the king, but only contingently. It had nothing to do with enforceability of a claim at court. It was a document which frankly was a written version of verbal agreements among peers which had long been the mode of community reconciliation. Innocent III showed then how an ecclesiastic community was transforming into a state apparatus when he rejected the Magna Carta: bishops withdrew services across England when so commanded by Innocent under Canon Law, and the Church as an institution could enforce this because it had (relatively new) apparatus for doing so.

Certainly jurists of the ius commune attempted to build an architecture which reified these submissions (whatever you want to call them: homage, fealty, vassalage) into legal language and law over the following centuries - giving us a formal basis of what has been called feudalism, and those contributed to a validation of claims over time as courts took their place in the machinery of government, with the prince moving to the centre of the court's claims of jurisdiction. And at the same time, the king became identified with the kingdom itself.

But whether something was the domain of the king or not really mattered nothing except as polemical claim; only the belief by others of the community in it, or ability to physically enforce the claim in war, managed to keep the medieval communities together.

That a king laid claim to domain was not substantive in the development of state. It was representative of ideology. The question is how those in the king's domain, whatever form of property ownership it relied on, came to accept the jurisdiction of the king. The question in 'development of state' then turns to something different, as Alan Harding summarized:

The history of the State has to be more than a history of strong government: it must show how an abstraction, a piece of metaphysics, came to dominate political consciousness as a thing not only believed to have real existence but loved for its promise of social order and hated for its threat of coercion.^1

Apologies for the density of this 'explanation'. Please do ask any questions and I'll expand or clarify where needed.

^1 Alan Harding, Medieval Law and the Foundations of the State (Oxford, 2001)