Does it matter? Distance from the capital provides some sort of limit against endless expansion by large realms, and the potential feedback loop that creates. Estates is not a fix, as estates only limits based on characters. Large successful realms attract more characters and thus perpetuate their own expansion.
The question should be, do we want a game that potentially ends up with a handful of large realms per continent, or do we want a game that encourages limitations.
Yea, but there are many means to achieve similar results. Sometimes, diversifying is good. Sometimes, it's just... too much.
Mechanics like capital radius and density limits have the players fight against the game. It puts a roof up to which the players can aspire to reach, and then... stop.
Mechanics like recruitment in the capital only modulate how competitive realms are via each other. If there's no player to oppose a realm, then the recruitment limit lets them keep expanding very, very far, until rogues become too much of a hassle, if even that. But against another realm, it'll give an increasing advantage to the losing realm, by giving them much shorter refit cycles.
Do we really need both kinds?
The problem with density was the lack of competition for titles and excessive contentness. Having too many small realms, even if dense region-wise, doesn't help with that problem at all, because lack of competition for titles and excessive contentness is worsened by the multiplication of small realms, because each realm adds a ruler/banker/judge/general/duke/marshal/vice-marshal.
I see the hinterland idea way more promising to help keep title competition without forcing realms to stop expanding and inevitably making the continents look like swiss cheese via the density mechanics like capital distance.
