warps are not place to place, they are just tempoary however alot of people seem to think that warps = teleportation from are to area on the world and portal = world to world teleportaion, not how it works, atleast not from the info we have.
however that is a technicallity also the portal hub is just an idea for when the game launches (my personal hub atleast) i think its just worth remembering that if this capital would be something that stays in the game even after 1.0 launches there might be a ton of worlds and a ton of ‘‘important’’ location in each world, so its either to build it logically and practically at first or to expand it later.