First, the developer doesn't need to take care of the handling, load balancing, logging, persistence mechanism and much more. As these services are provided by the EJB container. This helps the developer to concentrate only on the business logic.
The beam is designed in a very genuine way so that it can be run on different part of the geographical areas. So large scale business can be developed.
EJB container looks after the creation or deletion of the EJB objects.