Allow customer shipment without inventory moves
Some organisation does not need to manage inventory move per shipment. In other words they do not do "pick-pack-ship" but just "pack-ship".
Indeed they do wave picking (#4909) in such way that the picking is done with internal shipment (or even use robots).
So the idea is that if the outgoing location and the picking location of a warehouse are the same, the customer shipment does not create inventory moves and the user directly manage the pack step without the assignation (pick).
Also currently, the system is blocked if both locations are the same because the shipment will try to create a move with the same from/to location which is forbidden.
A similar design could be applied on supplier shipment but indeed I do not know about such work-flow.