The thing about positions of authority is that they really need to be abstracted. We consider them carrots or hooks, in which case they can be placed in their proper context.
So for instance if a position is a carrot - a goal meant to motivate players - then it's no different than a number of things on their sheet; just like there's a reason we don't just cram enough XP on characters to fulfill their every possible purchase since it'd remove the incentive, there's no point in handing out that Prince position in a political MU* to a person right away either, even if they can handle it. What we obtain easily we esteem lightly.
Likewise if the same position is a hook, serving a thematic purpose for the game ("who do I talk to if I want to convince House Poppins to lend us some of their umbrellas?") or to provide players with distinct roles ("you're the keeper of umbrellas!"), then they need to go in understanding their role. Niches are super important in MU* since ultimately there are so few unique roles; we are never the only sailor, healer or swordsman around, so these should be treasured but also, somehow, monitored. That latter part is very tricky.
Probably a good compromise is a mix of the two. I'd consider it a serious issue in most cases if PCs can hold the highest positions right away in a MU*'s lifespan, but a glass ceiling can harm as much as it can help, being a band-aid over a broader issue. There's usually no reason they can't occupy mid-range ranks though, especially since there can be more of those around, maybe with some objective/fair/non-terrible mechanism for advancement once players can prove they can handle it OOC before they move up the ranks.