That's because weak kneed politicians...and Communist sympathizers...wouldn't allow it.
Korea? One or two small,well placed,nukes just south of the N Korea/China border...and then a promise of "and there are more where they came from" from Truman...would have won it.
Vietnam? Kerry,Fonda,BillyBob Blythe,ILLary,Bill Ayers,etc.
So your argument is essentially the US military can‘t win it’s wars fighting like soldiers so therefore the military should be encouraged to mass murder tens of millions indiscriminately.
really ?