Keep in mind that for this, I'm essentially describing why I thought the D&D world implied by "10th level Aristocrats" was kind of a cool place. I'm not necessarily promoting this as the ideal or best way to present a D&D world. I'm just saying that for me, it was kind of neat to have a D&D world that conformed to these ideas.
Stormonu said:
The first is, of course that you don't only gain XP for combat. It could be quiet possible, were the queen to be a PC, that she could gain many levels for being involved in political plots and maneuvering. For example, she might get XP for resolving a squabble between two nobles and preventing it from escalating into a civil war. Perhaps she makes a royal appearance at the founding of a new library in her name and makes an inspiring speech that encourages other nobles to build other libraries - gaining XP for the act. And so on.
Theoretically, yes.
Practically, how many 10th level anythings have you ever seen or heard about who haven't been in at least a few combats?
This sort of D&D world is a violent, war-weary place, filled to the brim with monsters and demons. The idea that any character can be 10th level entirely through "ad hoc" XP like this is pretty unlikely on the face of it. The idea that even in a big urban center, she could avoid monsters, is also pretty unlikely. Monsters and battle are a fact of life for characters in this sort of D&D world, even for characters who are not PC's. It's implied that even farming peasants on the edges of civilization probably get into scrapes with low-level beasties of some sort.
That's part of why the world is appealing to me. It suggests that almost every NPC has an interesting story to tell about "that one time the ankheg got into the fields and we all got a militia together and stabbed it 'till it didn't move, even though it killed half of the Smith family" or "that group o' kobolds that wandered into the village that we had to take care of" or "when those cultists in the sewers came up spoilin' for a fight" or something like that.
It suggests that monsters are a fact of life, especially on the fringes of civilization, that even normal people regularly have fights to the death with these beasts. Given the fragility of most 1st level commoners, this implies a world where heroes are needed in daily life, where Adventuring is a necessary proposition, where mercenaries are something every farming village wants and needs. It helps create a more heroic setting for the party, and a world in which adventurers make sense, and are part of the setting, rather than apart from it.
In other words, XP is rewarded for the same things regardless of PC or NPC status. I wouldn't let a PC get to 10th level simply by giving speeches and talking to nobles, any more than I'd let them get to 10th level simply by getting in bar fights and drinking contests. They'd have to go be big fat heroes to get to that point. The same is true of Queen Victoria. She'd have to slay a dragon just like anyone else to get to 10th level. And if she can slay a dragon, she is probably not a frail old lady.
Then, of course, there are the kings and queens known for their battle prowess, who lead armies and plot against heroic characters (such as Queen Maeve who bedeviled Cuchulainn).
A 10th level Aristocrat Queen would be such a being in my mind: a legendary, heroic, magical, powerful Queen. If Queen Victoria were a 10th level Aristocrat, she would be a being of legend and might, not a frail old woman.
This is actually another awesome thing about the world this implies. While you can be a 1st level regent just fine, if the world has a few 10th or 20th-level Aristocrats in it, it implies that the world is a world of heroes, that great figures like this exist alongside the PC's, and that they party may eventually become heroes like this. It turns Queen Victoria into Queen Maeve, just like your 1st-level barbarian becomes Conan by 20th level.
And if she were a 1st level Aristocrat, she could still ably rule an entire fantasy-equivalent British Empire, without
needing to be 10th level.
Lastly, it would seem appropriate that the heroic figures of legend should have levels because they stand a cut above the rest of humanity. Good ol' Queen Victoria might have 100 hp because she's a tough ol' bitch to kill - she's important to the story and seeing her go down like a mook is a bit of a letdown
That's using HP/combat power more narratively than anything else, which is fine, but leads to Hussar's point: it doesn't make sense to not be able to easily kill a frail old lady.
My argument is: if you're a 10th level aristocrat, you're not a frail old lady.
And if you want a frail old lady, a 1st level aristocrat can do the job of being a ruling regent of a world-spanning empire
just fine. The fact that she's not 10th level doesn't make her any less politically powerful because in any edition of D&D that I know of, political power is from DM fiat (perhaps justified with a high Charisma and Skill Focus: Diplomacy and other things).
It's definitely not rocket science - but I can see where answering this question will lead me 
