I'm part of the BIBFRAME testbed group at Princeton, and the question of how to handle bf:Providers was one that came up last week while we doing data-entry exercises with the BF Editor.
The editor's default Monograph profile has a "Publisher" field that lets users create a "Provider" Entity, complete with lookups and associated URIs for bf:providerName and bf:providerPlace. However, because the current lookups only query
http://id.loc.gov, it wasn't possible to do anything with commercial publishers, since these don't get established in the Name Authority File.
Compared to the Provider Entity and its lookups, the free-text "Provider statement" field did seem like an odd appendage. Yet this is the field that RDA instructs us to choose, and our RDA-based cataloging only supports names established in the NAF--and since commercial publishers don't get established there anyway, we are stuck with not being able to make our data less "stringy" (the word one participant used to describe RDA).
In this regard, I think it is important to bear in mind the distinction that Kevin Randall drew between description, on the one hand, and relationship, on the other.
To Kevin (Ford's) point: