Stacks are even worse for bombing because only one unit counter is hit at random. I might be wrong but if the German focuses on using a lot of his air assets in a theatre to decimate one or even five Soviet units at a time, the Soviets are probably winning overall because you're not focusing on pocketing.
I agree that ground bombing can turn the tides, but Germans are getting at absolute max 300 kills per ground bomb run and ~6,000 disrupted (usually 1000-2000), which converts to 2,000/10,000 men in a rifle division = ~20% fatigue for ONE soviet counter. I do not want to spend any fighters doing this at all whatsoever.
Example below: the full complement of axis ground bombing took out ~4000 men, which less than one rifle brigade. Average disruption was 2,000 or roughly 5% fatigue. Look at the required fighter escort the Germans used. That translates to ballpark 10-25% fatigue on the entire Luftwaffe which means in turn I was able to take out 10,000 men and 200 planes as above due to limited LW interception capabilities. It's almost never worth it to stress the LW out for minor, minor gains (in the greater scheme) such as a few thousand men killed.