An M of N system is a multiple-input AND gate operation with a threshold value of M that determines activation of the gate (logical output of 1). Likewise, synapses form an M of N operation on the segments of dendrites in neurons.  Numenta is using this in their A.I. modeling of the brain.  But this "voting" (M of N gate) is not limited to segments on dendrites. The chemicals in each synapse and group-level activation of neurons are also a "voting" schemes above and below the segments.  These voting schemes are hierarchically nested not unlike city/county/state/country/world politics and work-team/department/division/company/industry/country/world in economics.  If these nested AND operations are only semantically different from NAND operations, then a complete Turing machine can be implemented by these structures. Each system has different methods of "wiring" the flow of the decision-making 0's and 1's (or the analogous analog signals) but those signals are always of finite supply and represent the finite supply of real energy or materials of the system to get the computational work done. In a corporation and government its money. In a brain it's food energy. In a computer it's CPU power.  If you are writing an evolutionary A.I. program to maximize computing power, the algorithms compete to obtain "money" that buys more CPU time.  This is the purpose of a currencies, so it should not be forgotten when working on Ethereum and Bitcoin that the importance is of a cryptocurrency is to define what the coins are referring to.  In bitcoin it is total computing power wasted. It works only because humans are making this wasted computing power a fraction of the semantic real-world value (dollars) which will ultimately be connected to transaction fees.  But POW and POS are not ideal: proof of capability is ideal, and that the actual computing resources be used to provide the ethereum-like contractual development and computations that are enforced by the associated cryptocurrency (which is a contract itself, unique in that it is what holds all the other contracts together and in some sense the top level).  The nested hierarchy of contracts is an algorithm seeking an objective in a way that distributes the coins to those agents that are best helping the system achieve its goals. Agents given equal votes in the design of the system is another currency based that helps keep the coins from being concentrating into the hands of a wealthy few at the expense of the health of the system (1950's style democracy and taxation prevented our current system of capitalistic and financial system oligarchy). In human society the goal should be to maximum median happiness per person to prevent excess polarization of happiness and wealth but also to prevent overpopulation by making it per person rather than blindly maximizing total GDP which destroys the biosphere without regard to human happiness.  

The current finance and banking systems are a 51% attack on the flow of currency in democratic countries. They have control of the core developers who were voted into place (the government).

So yes, it is great Ethereum is Turing complete so that it allows the above. But there should be an awareness by those implementing contracts on top of it that  there should be an ecosystem of contracts, that M of N is possibly ideal, and that the fixed-quantity of currency should be normalized to the total capability of the contract ecosystem to compute.

* Notes: Although more complicated with inhibitory (NOT inputs) and other things, the segments of the dendrites and dendrites can be logically restated to an equivalent Boolean operation of NAND if not AND gates, because the difference between NAND and AND gates might be a semantic definition of "NOT" on the inputs.