Unlike Ark or Atlas, natural depletion of resources will cull large groups. They can farm hard, sure, and last for a while, sure, but the nature of space - and the time it takes to access resources becoming greater and greater - means large groups would have to deal with efficiency at some point. It is a natural, physical property called the "inverse square law". Ark and Atlas had infinite resources, so these large groups were able to just leverage more of these free resources to outdo their opponents. However in the physical environment of Starbase, a large group cannot just send 1000 ships to attack. They will be vulnerable elsewhere, spend great amounts of fuel in doing so, and every ship they lose is donated resources to the more experienced team. There is no free resource in Starbase. There is no free movement of ships like in Atlas. There is no infinite spawning of resources like Ark. Everything has its cost, and that means large groups will only be as good as they are efficient and able to both plan and execute their gameplay desires.
If you think of Starbase like Ark or Atlas, and just go in swallowing up all the resources and burning them fast and hard, eventually you will meet the inverse-square law present in the game. Players and game systems consuming your resources wastefully and so on will lead to internal collapse. This was not possible with Ark or Atlas, and so yes, large groups just had more free stuff to do everything with. Starbase seems to be able to counter that where even if you have a lot of people - they are all consuming large volumes of resources - meaning every death and every ship lost matters - and how effective your large group is becomes more important than how many people you have farming free resources out of the ground.