Also I think he's trying to give the notation that having a character that relies on the help of other characters is a bad idea especially if your goal interferes with their own. Also if none of the other characters agree to go with you, you pretty much halted your own characters progress incidently. I think the idea is that eventually your character would cross paths with every other player eventually to create a web of arcs and ultimately building a world that would eventually be affected by the GM's hand later on (I'm assuming)

If two characters decide to travel together than your actually halting the progress of building the world around you. It may not of been intentional but it does happen.