Well the biggest problem with that is the ongoing problem with rebels in general, ever since STW: it's a catchall faction. This means the rebels in Ireland, and the ones in Antioch, and the ones in Cuba, are all on the same side as the ones in Scandinavia. So for the most part rebels got their ability to develop as a faction nerfed, and were given random spawns to make up for it. If it had strategic cohesion, it would be the largest single faction in the starting game.

I wish every rebel province was treated as a separate faction. Then we could get rid of that "as-soon-as-i'm-at-war-with-the-rebels-i'll-never-be-able-to-make-peace-with-them" thing. I want to see rebels provinces as individual minor factions first. It wouldn't really be a lot of work creating their unit lineups, most would be near clones of the dominant powers in the region, with deletion or substitution or two.

Then we deal with them having strategic units.