The old pre-2.1 mission board used to, very occasionally, offer a permit to a permit-locked system if a faction from that permit-locked system was present. For example, if you were in Cemiess and an Achenar faction had expanded into Cemiess, then you'd sometimes get that faction asking you to go to Achenar. At the time, there were a lot of other "lockouts" for missions (eg. rank-lockout) so if you were a newbie or simply new to an area of space, you'd often end up with a mission board full of missions that you weren't allowed to accept.
So, most of those lockouts were taken away. To take away the permit-lockouts, they simply forbade missions to permit-locked systems from being generated.
Which is a shame. The superpower capital systems are great for giving out missions, but it's always a "dead-head run" going back empty the other way. This is especially true for passenger ships, which can't take on general cargoes for delivering back to the capitals. Personally, I think there should be loads of passengers wanting to go to their respective superpower capitals: politicians and diplomats, protesters and lobbyists, terrorists and tourists.