Why should Demeter be the ruler of Mt Olympus?

I would imagine that Demeter should be the ruler of Mt Olympus because she controls the seasons which the Greeks would need most in their lives because the majority of them would be farmers and would need the seasons to be controlled so that they could grow good crops and be able to survive. Therefore she would be the most important goddess because she has the most effect on the average persons life.

Answer 2:

Demeter was not the ruler, Zeus was.