The reason they don't exist is that even if they worked for free, they can't offer any "Nobody ever got fired for hiring us" value, so nobody doing SAP implementation will hire them.
Anybody who can afford SAP can afford to pay the full freight, in which case they want the full package including insurance against being blamed for problems.
I was going to add that boutiques can charge the same rate as the big firms, but they do so in different markets. One example: Above I noted that the person buying the service has downside of being blamed but no upside for saving money.
That isn't always the case. When the person making the decision is also under a lot of budget pressure, boutiques can make the same hourly rate by being more productive. That productivity often comes at the expense of insurance against blame, for example you can't have as heavyweight a process.
But if you are working for someone who cares about the money, being more productive can get you the gig and the rate.
The few boutique SAP shops that exist generally charge twice what Accenture charges, since they are staffed by top people with a proven track record of getting the job done after Accenture have failed.
They don't exist because a certain deadness of the soul is required to do SAP implementations. Anyone who has done it will understand what I mean.
Your information about what share of revenues individuals receive is wrong in my experience. They way this business works is that a project gets staffed with a few who know what they are doing (and are often not employees), who may get 100% or more of their nominally billed rate, filled with the 1/3 to 1/8 people you mentioned whose main task it is to look busy and not say too much.
I remember some wit on Slashdot commenting that "SAP is how Lucifer interacts with our world". Having had some experience with various Tier-1 ERP systems I suspect there may be some truth to this theory.
In my experience the only people making >100% are the partners. So you are correct that they are not employees, but not necessarily that they know what they're doing...
