I mean having 100 different countries on a planet, each with space age technology, there would be a problem. There just wouldn’t be enough real estate for that many countries to stake claims and progress forward. On the other hand if there was only a few, say 2-4, countries with space age technology it might work.
I see it going as not having to unify to progress onward, but giving a detriment (based on how many other countries with space age technology there are) to players if they decide to not unify.
I don’t necessarily see it as a problem in the early space stage. But the internal conflicts could really make it difficult for you to progress to a galactic empire stage. Though I suppose even then the different factions from your starting planet could claim their own solar systems, so you could keep playing against them and competing. But maybe there could be some harsh penalties to encourage players to unite their planets. For example your rival factions could get a huge boost for researching tech you have, so it would be way more difficult than normal to ascend first.