In nazi germany case, it feels part of the problems were the doctrine and lack of ressources to produce/maintain/fuel enough and they also kinda had their max crisis with the heinkel 177. Udet seemingly obsessing over dive bombers also didn’t helped. I think if they did more, nazi germany ould’ve still bombed cities and I do reccall reading that japan also did its share of bombing in asia. Japan also had bomber programs but often didn’t got past the prototype stage either due to the war stop or lack of ressources to produce them.