You're missing the points of failure and the complexity of dealing with them. If the truck supposed to be servicing one leg of the journey has a breakdown, or the driver goes on sick leave, suddenly every container that was to pass via that leg is now stuck. Instead of having 1 spare long haul truck that can do the full journey, you have to have a spare truck per leg (Or you have to send your redundant truck on a long-haul drive to replace the broken truck, and then have them work overtime to catch up with the backlog of containers)

You also lose throughput by introducing potential handover delays. You end up with a bloated admin that is continuously having to fix a shifting constraint as certain legs become bottlenecks, etc.