Hi. the default environment is the one available to anyone on the organization. As such it's difficult to put any real security controls around it. Folks setup named environments to meet specific organizational purposes they have - just like in traditional IT environments, where you may want an instance of the system for the IT group, another one for Product development, etc. Having the ability to setup multiple environments is an enterprise strategy and capability that Microsoft provides. That way each instance could have its own security, customizations, reporting, etc. It could certainly be it's own topic, you are right! In a smaller organization this may not be relevant, but b/c Microsoft builds these solutions to be 'enterprise scalable and ready', this kind of functionality is pretty critical.