Hard lessons learned in WWII. One example: The Russians were able to hold Stalingrad and break the Wehrmacht because the Krauts leveled the city, providing almost limitless cover for the Russians to fight from.
When we leveled the Benedictine monestary on top of Monte Cassino in Italy with a huge bomber strike, we totally detroyed the structure, but killed few Germans. When the dust settled, they simply had a million new fighting positions.
That's what is being referred to, I think.
Yes that is probably true. But we did not bomb the rubble and the Germans didn't have B-1B's and B-52's.