You might be right with that observation to some degree but rear shocks arent statically mounted and do allow for some forward and backwards movement unlike the front suspension.
Exactly my point, you have shocks that are not statically mounted (on either setup) but the trajectory of the traditional setup is down and forward and it gains travel by moving foreword. Example, I have a bypass rack with 4.0s with 16" of stroke, however it gets more than 16" of travel because it is not 1 for 1. However, if you have a setup with vertical shocks or a staggered setup with forces pulling both directions it seems your rear end would move straight up and down making your travel closer to 1 to 1 and limiting potential to gain more travel through mods without switching from a staggered setup to a more traditional setup.