At heart, you have risks, and you have rewards, and these can be improperly assessed, and unfairly allocated, under any system.
Ultimately, it depends on incentives, social and monetary. If you can make a lot of money gaming the system, and this is seen as "success", then you will game the system, however well it is designed.
My job as a banker, on any project, is to try to outthink the people that will try to game the system, and put contractual safeguards so that they can't do it. It can also mean, simply, choosing to not work with some people because, no matter what safeguards you put, if they are in bad faith they will always find a way to fleece you - or try hard enough that you waste a lot of resources preventing them from doing it.
Just like there are no manthematical models that give you an exact number on what risks you are taking in a project, there is no legal framework that will protect you against human nature.
Thus the need for bankers, exercising judgement and able to understand what the underlying project hypotheses are and to evaluate them. It's, fundamentally, a qualitative job, not a quantitative one. In the long run, we're all dead. John Maynard Keynes
IMHO these partnership mechanisms are emerging in use - as did Income Trusts and Royalty Trusts in Canada and Australia - because they share risk and reward in a pre-distributive (sharing gross revenue or production) way that some investors find attractive.
It is therefore possible using such frameworks to raise necessary credit or investment "Peer to Peer" from stakeholders.
This is clearly more efficient - Coops call it the "Cooperative Advantage" - than to go to unproductive rentier credit or investment/speculation intermediaries who are interested only in making money from money, as opposed to being paid for the use of value/ money's worth such as location, energy or knowledge.
The need for banking as a service remains, both for:
(a) managing the process of bilateral Peer to Peer credit creation;
(b) bringing together Peer to Peer investors in productive assets with investment in productive assets.
Why go to to the trouble of setting up completing claims over productive assets - ie those of secured debt and equity - when it is simpler and less conflicted (not to mention fairer) to share production proportionally?
But your point re human nature is absolutely valid. Although I believe that the partnership framework is capable of aligning stakeholder interests in an optimal way, that still does not mean that people will agree, or continue to agree. Partnerships are not a magic bullet, because human beings are fallible. "Any economic unit can emit money. The serious problem is to get it accepted" Hyman Minsky
