The Ethereal Writer Redux wrote...
This is actual lore, FWIW. Not just a well-educated guess, but lore on the matter. At least, insofar as we're aware. For all we know there were non-Mage rulers in the Council of the Dales that ruled them alongside the Mage rulers (maybe a scarce amount)
However, to say there was a divide based on the absence of evidence simply because Mages were ruling is, IMO, not right. We see in DAO how the elders' word is so valued amongst the clans that it carries a lot of weight in talks with the Keepers, and we see non-Mage Elves in important roles (craftsmen, storyteller).
But, on the other hand, we have also seen a Keeper completely ignoring the Elders of her clan which should illustrate just how much real power they have AKA what little the Keeper allows them to have.
It's true that there are non-mage elves in important positions but we also witnessed a; supposedly; non-mage human attending an important party in Tevinter because he was a procurator of slaves to the Imperium. But that doesn't change the fact there is an amazing bias in favor of mages in Tevinter .
Honestly, I believe we can logically conclude Dalish culture places an emphasys on mages over mundanes. This is because the entire purpose of the Dalish is to "restore what was lost" and part of that is a legend about how all elves used to be mages. Meaning that, logically, the Dalish will consider a mage elf to be closer to being an "ideal elf" than a non-mage.