For years I have been writing reviews about size control and I always am stumped by what to say we should expect if there is no size control mechanism in place, i..e there is just a fixed set of subunits and they self-assemble but no additional system is measuring or modulating the size. what is the null hypothesis? the answer is not at all obvious and so what they have done in this mansucript seems very important to me, since now we can define in very precise terms what the null hypothesis should be. If the authors are looking for good examples of cellular sub-structures whose sizes are power-law distributed, one example is IFT trains (see Ludington et al, 2013).
-Wallace Marshall, UCSF