I deal with consultant price negotiations all the time and quite frankly it's one of the hardest challenges that consulting companies face. I think I might have lost you with my rent-a-center analogy; my point actually was to say that they aren't like rent-a-centers. In the case of a consultancy assessing the value of these transactions is extremely difficult do as a customer and more importantly as the owner of a newly established consultancy owner. Not to mentioned some of those transactions hold more value (and thus price/hr) to different sets of customers. This is really where the unfortunate math behind a starting a consultancy lies. At maturity (i.e. when you have consistent client pipeline) these are much easier to decipher.
EDIT: I just realized I did actually say "let's pretend a consultancy is a rent-a-center". I should have probably worded that differently - hence the confusion.
FYI, I find the conversation fruitful! The criticism is much appreciated, and readers will do well to hear your counter arguments.
I very much agree with your points, especially that "billable hours" is not the point, that expediency or rarity of talent can easily be more important.
A fuller, more accurate treatment of the concept has to include that. Perhaps it's still useful for folks to (sometimes!) think about optimizing the person/hour, since that is of course an important part of the equation, and optimizing it does help.
EDIT: I just realized I did actually say "let's pretend a consultancy is a rent-a-center". I should have probably worded that differently - hence the confusion.