RMIM seems a bit counterintuitive. How is that any different from 2-finger?
Quite simply the hand is divided into two distinct sides and functions. Thumb, fore and middle finger are controlled by one set of functions mainly for dexterity and the ring and little finger are part of the power or strength side of the hand. The ring finger shares a partial function to both sides. Now look at it again with this info and in using a standard two finger or in holding a pick you are using one function, so it is simple.
In a three finger that uses the ring finger you are using two functions and trying to make them work as one.
It is the nature of the bass that these conflicts can and will happen because the reality is you can play it with any number of fingers, pick, or a bow.
Original Fender electric bass guitars were designed to be played with the thumb, that's why the finger grip was placed where it was.
As more and more player start to use the bass guitar in a manner it was never designed for, the need for new techniques and borrow techniques from guitarists will become the norm.
Does anyone think that pianists debate the direction or the number of fingers they use in order to play? The idea that the fingers should only work in one direction or in one way is ridicules to a pianist, so it should be ridicules to bass players as well to put lots of time and effort into making them so.