I agree that the whole concept can be confusing. But to use it, you don't need to understand the technical details. All communities can be viewed from any server (except if the server decides to block it).
In my opinion we should focus more on communities and less on where the community is hosted. How to do this, I don't know.
Also all the tracking and analysis tools that are integrated in most ecommerce are huge. We made a website for a company that was really fast and snappy. Then they added all their tools and it turned into a slug.