Why New 'Lunar' Republic?

To whomever who grace my user page with your presence,

NLR is a somewhat popular fan concept in the fandom. I don't claim to possess much knowledge in the related world-building process, and I sort of understand why Luna is an obvious stylistic choice for a duumvirate Equestria setting. But besides, I always feel kinda weird that Luna, arguably one of the most reactionary ultraconservative tradition-bound figures in the show, would come to be associated with a revolutionary republic. If Celestia could be likened to Queen Victoria,, I figured that Luna would definitely be her Ernest Augustus. At the very least, it is hard to see her favor any system other than a monarchical system with good top-down authority.

First, did I make wrong assumptions about the NLR setting e.g. it is just like a guardian coup d'état? If not, then setting-wise or plot-wise, do you think it could be relevant or that it's just largely a 'meh' issue?

Thank you.