Hi !
How do you setup two softbodies with collisions without getting a dependency cycle ?
A depends on B through Softbody Collision
B depends on A through Softbody Collision
Those two objects interact with each other. It’s pretty obvious that one depends on the other through collision. Why does blender consider this as a problem ?
Nobody ? 
Can’t give you an answer as to the why. All sims in Blender have lots of limitations. Probably just nobody around to do the work improve it.
In any case, I agree that in a perfect world this should not be a problem. There is no physics-related reason. But it is the way it is. The only workaround I know is to enable self-collision and merge all bodies into one object.