Not all states are the same, clearly; and I have already spoken of this in this thread (Constitutional Monarchy of the UK, US is a Federal Republic etc). However there is a well-established definition and understanding of what does and does constitute a state. For example, I can’t just declare my home an independent country.States are not all the same.
The early modern state developed in ways designed to feed a centre – Paris, Moscow, Stockholm, wherever. Effectively they developed as a kind of vampiric function of the centre. If lucky over time they reformed away from that, to allow redistribution and regional development. Though France (Paris-focused) is more centralised than Sweden (Stockholm-focused), while Russia still has moved the least from the original (Moscow-focused).
Frankly Brussels doesn't work like that in relation to the EU. (Though fantasies about it persist.)
It's somewhere to keep the joint luggage. And it does the agreed redistribution of funds.
As I’ve requested before – Germany is not a state; kindly prove me wrong…
Brussels (legislature), alongside Frankfurt (financial) and Luxembourg (judiciary) perform the same functions as the capital city examples provided. Brussels is where the redistribution of funds collected from the provinces/member states is then returned back to the provinces/member states to be spent as per the agreements or instructions/restrictions of the central authority responsible for allocating funds, as your graph demonstrates.
Did I miss anything?