Carpet bombing New York would have vast negatives - pretty much all of New York would...
After a carpet bombing, I doubt it... ask those German and Japanese cities... the survivors usually have not much will to fight more and get more bombs. There's a level of horror that breaks any will people have.
In Vietnam, Iraq or Afghanistan US tried, and is trying, of course without success, a "limited", "humanitarian" war going against only some precise targets - that type of war can't be won without support from the population.
In Mogadishu they were caught without tanks against more heavily armed enemies with no fear to kill them - and it took old, yet useful against that kind of enemy, Pakistani tanks to save them, the Somali couldn't stand their firepower, and had no weapons against them.
B-52 in Vietnam were used only in the last stages of the war. Before most of North Vietnam coudn't be targeted because of the political implications as the ports couldn't be mined for fear of blowing up Russian or Chinese ships.
But if killing people, any people, is not an issue, look at how ISIS could take control of whole cities even without tanks - just terrorizing the population. But of course they couldn't stand a force with bigger weapons than theirs determined to fight them (the Curds, on the ground, still with support from artillery and planes).