DS9 certainly took it to a more intense point, but there's not a single Star Trek series that wasn't constantly swimming in politics, philosophy and ethics dilemmas. Anyone who thinks there isn't real life politics in Star Trek isn't paying attention.
Most of the other series were more philosophical. It wasn't really about the long-lasting impacts of politics, rather more just thought problems that were wiped away at the end of the episode.
I think that's what OP meant when they said "...politics in ways the other series never did".
Moogie is great. I love the scene where she is explaining some sort of investment she has to Iggy-Pop Vorta, who then responds with something like, "As fascinating as this is, if your son doesn't collect you soon I'm going to have to kill you."