If one commits to one side, you are in or out. If one hem-haws around and then says "I'm neutral y'all" they get a lot of wiggle room. They can be flip on Monday and flop on Tuesday. Yes, some of the residents get a bit testy and there may be a lot more feuding going on but the politcal clout was very clear. If those in the 'free space' had slaves, they didn't have to turn em loose when the EP was read aloud. They could let a US group camp out and maybe take some stuff from them and sell it to the Confederate troops who used the campground a few weeks later.
You get the 'neutral' nations, such as England, and ya see how well they played that game. Neutral meant 'no commit'='no consequence'.