A leader (or at least one that wants to build a stable base of power) needs their immediate subordinates to believe in their legitimacy. The foundation of power is obedience, and the belief that you have the right to give commands that ought to be obeyed is a very effective mechanism. An election is one way to secure that legitimacy, no matter how foregone the conclusion or how large the body of electors.

Historically, you might look at the Holy Roman Emperors and the prince-electors that (at least formally) chose them. What matters is that some people obey some people who obey some people who ultimately came to the consensus to all obey the same person.

(Of course, that obedience based on legitimacy may have limits, depending on the principles underpinning that legitimacy. If the foundation is god’s favour, the impression that a ruler is losing that favour may well threaten his power as well, which is how you get kings pleading with the pope to retract his excommunication: if he doesn’t, his vassals might withdraw support.)

So, yes, some circle of people who are commonly accepted to have that power elected him. Nobody said it has to be a fair election, so long as the important people respect its result.

Ankh-Morpork had dallied with many forms of government and had ended up with that form of democracy known as One Man, One Vote. The Patrician was the Man; he had the Vote.

– Terry Pratchett, Mort

A great many authoritarian systems throughout history, especially in the ancient world, have had a selection system that formalises compromise between the major power brokers to prevent the whole group being made easy pickings to outsiders by succession struggles.

Primogeniture is not the default because the oldest son often sucks.

The electors here are influential clergy members and high ranking military officials.