Carpet bombing was the only way to do it at night. Without radar, CEP was about five miles. Meaning that half the bombs fell within five miles of the intended target, not enough to hit anything else than a metropolitan area. With radar, the CEP at night or through cloud cover was about 1 mile, enough to hit a smaller town. Daytime "precision bombing" CEP was about 1000 feet, still a far cry from smart bombs but enough to hit an industrial target.
Strategic bombing in European front did succeed in two goals: destruction of Axis POL plants did wreck the mobility of their armies and eventually throttled their entire logistics (though only later after it was found out that factories were quickly rebuilt). Secondly, it tied over a million men, tens of thousands of guns, and an entire Luftflotte away from the frontlines.
In Europe, with stone and concrete buildings, established fire brigades, and ample bomb shelters, the direct destruction caused by carpet bombing was not that great though, and as said, factories were often quickly rebuilt. Against Japan, however, it did succeed; cities made of wood and paper, with insufficient firefighting capabilities or bomb shelters were wiped out with firebombs, dropped at low altitude for increased accuracy - the firebombing of Tokyo killed more than the two nuclear bombs combined and destroyed most of the city, civilian and industrial targets alike.