Are tacos a universal food or is it unique to Noxus?

For the most part, I'd say it's Monarchistic Stigma: No matter how amazing some Kings and Queens have been, Humanity as a whole is progressing towards the Democratic Standard (that is, we want to choose who our rulers are by collective vote rather than the hereditary model of old) and we generally consider Monarchies to be 'backwards' in the sense that people can't choose their ruler and thus can get stung by poor genetics. Not everyone likes John Oliver but I loved this segment he did regarding monarchies.

There's also the Collectivist Stigma: Collectivist Socities tend to discourage (or restrict, sometimes forbid) the growth of the individual in ways their society may not approve of. Fiora would arguably be capable of leading her house, but their society continually pressures her (and tries to force her) to marry men she's not interested in.

Noxus is Imperialistic, Cruel, and Racist, we know this, but they are, ultimately, a Pragmatic Meritocracy where even Swain, who was a cripple, was able to politically maneuver himself to become Grand General and yes, Katarina and Kled disagree, but that's their opinion.

Demacia, by Contrast, is Sexist and Condescending. You can work your way up the ladder, sure, but you'll really have to work for it, and even then, there are places you'll never be allowed simply because you weren't born a Royal.