An example that I'd point out is the only 'political party' that actually got proper spotlight in Endwalker (and the one I'm most confident is actually a political party): The Bibliothecs, in Sharlayan. Out of all known political groups they're probably the one with the most cohesive known platform, as well as debatably the one we can most quantify in terms of members and influence if we're really clever about political analysis. And their place as basically Astrologian's antagonist gives us a decent window into how they work.
But even though they're around, named and even seen in Endwalker, they don't actually get a whole lot of spotlight. Because ultimately, the level that political parties/movements mostly work on just don't really exist for a story like the one we're playing. Our main area is basically international relations, so we know how each nations' political forces operate there as well as a couple region-specific issues, but everything else just doesn't really matter to us. I'd argue that it never could've; even a theoretical version of 5.0/6.0 that focused much more on Garlemald wouldn't have done much more with them.
I hate that we spend so little of the Garlemald content talking about the incidentally-liberated slaves down in the oil fields, but I also don't think the story ever actually had much scope to talk about them.