If you have a few more Docker hosts, how are you going to manage them? Running a tool such as Portainer is great, but it can get troublesome when attempting to manage more than a few hosts. Also, if you are running multiple isolated Docker hosts, you do not have the option of moving containers between hosts.

Sure, you can use tools such as Weave Net to span the container network across multiple individual Docker hosts. Depending on your hosting environment, you may also have the option of creating volumes on external storage and presenting them to Docker hosts as needed, but you are very much creating a manual process to manage the migration of containers between hosts.