It always comes down to AI and, to a lesser degree, player expectations. People claim to want alt-history and sandboxiness, so vanilla HoI3 had very little restrictions. Jesus christ the shit storm on their forums when WW2 didn't start on 1st September 1939 with Germany attacking Poland. Or France stood their ground. Or Any of the other myriad thing that could happen - fascist USA being prime example. So turns out that vast majority of players actually want the WW2 to go exactly as it historically happened, except that the country that the player runs should have 100% freedom to do any- and everything. Whoopie, players are retards, news at eleven.
So France had to be nerfed and Germany made even more op, so that AI-Germany could reliably roll over AI-France, which then meant that War in the East is usually over in 3-4 months, no matter which side wins.