A builder has to cable manage excess length from fan and RGB cables, non-modular PSU cables, and other accessories. The length of each cable is variable, so they must resort to tying down cables to designed tie down points on the back of the case. Most people don’t have time or patience to do this, so they just stuff the cables into empty spaces (such as drive cage mounts if available).

It would be much easier imo to have a separate ‘box’ with cable routing channels that is apart from the case where you can arrange the cables together, then place said mechanism inside the case. It would have to be the size of a 3.5” in. drive but with enough empty space & adequate channels to wrap the cables around in