The way that planets work, it seems that planetary input is really the only thing that matters in the game. You have buildings, you have citizens, and they let you get percentage gain. But... if your planetary input was 3.... A 50% gain is still just 4.5. It doesn't matter how many manufacturing plants you build.... your planet is never going to manufacture. If, on the other hand, your input is 8, then 50% gain gives you 12, which is a huge boost, more than the other planet even makes.
The problem is that planetary input is random. It's like you're playing dice, and if you roll high, you find and colonize planet Fantastico... That's it, you're going to do fantastic. It's like Guns, Germs, and Steel: The Game. Nothing you do matters, just where you live.