That restriction is needed in some way to prevent that building being a way of teleporting stuff across the planet. They did relax this in 2.1 and allow you to build extensions to that building where you can add inserters and use belts/trains.
you can't teleport things with it. the landing pad allows only withdrawals, not deposits.
I think this conversation is confusing two things. There are two kinds of exploits that would be possible via the landing pad if certain restrictions didn't exist:
* If the landing pad allowed insertion as well as withdrawal, an arbitrarily large landing pad could allow item teleportation by inserting at one point and withdrawing at another
* If multiple landing pads were permitted on the same surface, items could be teleported (in O(1) time, not 0-time) by launching a rocket from one side of the factory to an intermediate surface (planet), then launching from there to a landing pad on the other side of factory on the first surface (this exploit is explicitly _allowed_ in Space Exploration, the mod which inspired Space Age)