Whike i can see where you're coming from. That only really works if the political movelents work well. The equalists fight against bender supremacy, except that's never shown. The Red Lotus believes in anarchy but never goes into detail about what that entails either
Each season tackled a completely different global conflict because Korra’s world was undergoing a rapid industrial revolution. Having multi-faceted villains tied to distinct political movements across 4 seasons is far more impressive writing than stretching one standard warlord over 61 episodes.