You are correct, a role with just a name and domain is a valid governance output, but we don't recommend it as best practice. We added the red incomplete role indicator to the org chart to highlight this to support better Holacracy practice. But, in the spirit of continual improvement in Holacracy, it is really something to improve rather than invalid governance. Maybe some help text is in order to make that more obvious to folks.
I think one of the ways that HolacracyOne can increase the spread of Holacracy is to use our strength of Holacracy expertise to help folks be able to practice it better. So, we try to infuse that expertise into GlassFrog to support more folks in their Holacracy practice.