I think the point is to save time in global games. By far round 1 is the slowest round because you are shuffling and merging and re-stacking everything. Even though you more or less know the set up after a few games it takes time because there are units everywhere. This is very much true for Germany, Russia and japan but goes for all other nations too. For france you set up a bunch of units which are removed instantly.
After Round 1, there are units in maybe half of the initial territories and this must save a lot of time.