(Not a shipping cargo person, so take what I say with a grain of salt) The value is cross-loading delivers greater network effects. You have many possible path

(Not a shipping cargo person, so take what I say with a grain of salt) The value is cross-loading delivers greater network effects. You have many possible paths to get to your destination, and can pick the most optimal for your particular needs at each step. Most container ships are on a sailing schedule - they visit a set number of ports, and generally stick to it (absent other issues). So you can get out of your origin country quicker by just picking the next ship with the cheapest rates going to approximately the right location. For the shipping lines it's more efficient to just pick up a lot of containers at once and visit multiple ports than try and get a full load to just one destination. It also means that each port they visit they're also getting paid for new cargo for onward destinations, not running empty (or waiting for another full load) to do another trip.