I was inspired by Go's use of URI as a namespace for user packages, and short names for the standard library. I thought it was an elegant way to allow everyone to host anywhere, and dodge a lot of complicated namespacing issues.

One design principle that was very important to me, was portability and avoiding fragmentation. I wanted every image name to have the same meaning in every engine, so that when writing a Dockerfile, you could have confidence that it would actually behave the same on every docker installation. In this we disagreed with other platforms (like Red Hat) who sought to "embrace and extend" Docker by changing the meaning of short names. We always fought this to avoid fragmentation of the platform. This did not make sense from Red Hat's perspective, since they were the platform - who cared about fragmenting Docker? That led to some negativity which is probably what you're remembering.

At the same time early Docker users wanted the ability to host their own images without being forced to use our central registry. Using Go's system solved both problems at once.