Can you go into details how you think this would work? Or if you have covered it already in a previous post, can you point me to it? For PP at least, it would add to the area you need to control, and presumably in a direction away from existing colonized areas, meaning further from your capital, meaning harder to maintain, and PP is already a game where you have to run harder to stay in the same place the more you expand.
For the BGS... well, if you are set up out on the edge, perhaps, but then, i don't think there is much competition for systems out on the edge anyway.
How could it be blocked? And why would anyone want to block it. So, you're looking to colonize a system out on the edge of a bubble. Why would anyone care? Go right ahead, be my guest.
Therein lies the crux of the matter, the location of these fiefdoms. Whilst those who want them will say on here that they are quite content to be out on the edge of nothingness what they really want is to carve out their little bit of space in the bubble. Unless they can interact with everyone, proclaim their sovereignty over the system, who will know they exist! Rest assured they want to be right in the middle of everything, you don't build the biggest most fortified castle where no one can see it!
Just look at the OP's credentials: He is the Sky Marshall of the Earth Defence Fleet. Why Earth, it isn't home to any of the major faction capitals, heck the system is permit blocked, there is nothing to defend. But it sits right in the middle of the bubble, lots of traffic to exert their power over, can't do that when you are stuck on a rock 10,000 lys from the nearest populated system!