The FAQ explains why the threading is limited. I'm not sure I agree. I've just tested threading in the sandbox and the threading level is very limited: after two replies threading starts getting messed up.
I've participated in many fruitful (and less full) discuttions in various Wiki projects. Often a discussion starts as a flame at level 1 or even 2 and ends up properly clarified after some discussion. Nesting allows discussion of finer points.
So, can one use the Flow platform to discuss this issue and make a good case?