I would say that "Consulting" model as defined above is employed moreso (but not entirely) by Deloitte, but Accenture and Booz Allen have a higher percentage of on-site folks not at all engaged with internal IP building, sales, etc that amount to staff augmentation. As Booz Allen and Deloitte went after service contracts typically held by folks like Lockheed, GD, CSC, etc it was a race to the bottom for fees to grab as much land as possible, so there wasn't really any head room for people that could do both in the rate they pass through to the customer.

Furthermore, in the cleared space you're pretty much silo'd to places that grant clearances - so while you might build up some IP you can never actually leave that market because your credentials are too valuable.