Yora
Legend
I think actually you could take that statement even further and say that the factions are the "environment" of the setting in place of geography. Through the selection of factions you pick, and the choice which ones you don't pick, you are defining the theme and tone of the campaign. Even though the players would have the potential option to go everywhere and talk with everyone to do anything, the main factions make up the pool from which both trouble and help will come to them. As GM, you have complete freedom in take a character from anywhere if you're in need for an NPC for a specific situation. If you keep drawing a majority of such NPCs from the factions then you're automatically steering the players back into the network of faction conflicts. The players have complete freedom to go anywhere they want in physical space, but almost everyone they know who can provide assistance and advice that could meaningfully help them exists in that network and they don't have anywhere else to turn to. And in turn, any favor or service they are asked for in return will further draw them into that net.
Potentially, this net could even exist over a large part of the galaxy, but it might also be just a single star system. Since distances are illusionary in settings with arbitrarily fast hyperspace speed, it is the size of actors in the network that determines scale, not distance. Especially when using a system where time tracking is highly abstracted or nonexistent.
Six major factions that define the setting for the current campaign (though not necessarily the whole of the fictional world) seems like a good maximum number. That gives you a good breadth of different factions and also different types of factions and a total of 15 relationships between them (if my math doesn't fail me).
Potentially, this net could even exist over a large part of the galaxy, but it might also be just a single star system. Since distances are illusionary in settings with arbitrarily fast hyperspace speed, it is the size of actors in the network that determines scale, not distance. Especially when using a system where time tracking is highly abstracted or nonexistent.
Six major factions that define the setting for the current campaign (though not necessarily the whole of the fictional world) seems like a good maximum number. That gives you a good breadth of different factions and also different types of factions and a total of 15 relationships between them (if my math doesn't fail me).