Strategic Allied bombing of Germany during WWII was ineffective in many raids. Yet they still inflicted substantial reductions of industrial output, and other critical aspects of the German war effort. It is estimated that it reduced overall potential output by as much as 35% by the end of the war, despite some critics suggesting it played very little role. The raids also disrupted transport, a vital aspect in moving supplies and shifting troops to other fronts quickly. They also specifically targeted petroleum production as much as practicable, which greatly hindered the German war effort in the last year or so of the war. The fact is, the Germans would have had much less trouble, in all aspects, of prosecuting the war against the Russians if the raids had been suspended by the Allies. So the raids certainly suppressed a substantial amount German capabilities, at least by 1942 and after.
Moreover, the Allied bombing also caused the Germans to retain many army and air forces in men, aircraft, antiaircraft batteries and support staff. These were critical assets that would have been much better served destroying Red Army concentrations on the eastern front rather than blasting away at Lancasters, B-17s, and B-24s, etc. Stalin complained about another front, but the British and Americans were already at it in the air. And paid a heavy price, with combined losses of airmen over 150,000 KIA. The Allied air crews were the bravest men of that war. The risks were enormous against German fighters and flak guns.
However, the Germans had the potential to make jet fighters years earlier. Realistic estimates suggest they could have been flying many such fighters as early as 1942, with speeds much faster than the finest of the time - one being the Supermarine Spitifire. (It should be noted that the Spitfire is the only fighter to be made before, during and after WWII, a testament to is superior design.) The decision not to build jet fighters was of course Adolf's. He never trusted advanced technology, and initially insisted that the V-2 rockets were nothing more than glorified artillery, which is true, for standard explosives. But he finally went with the V-2 since he thought it might be the super weapon they needed, and allowed for small numbers of ME-262s to become operational. Of course it was all too little, too late.
The big "What if" :
Could the Germans have built an air fleet of jet fighters to eliminate the Allied bombing raids earlier in the war? Perhaps someone can provide an idea of the real capability of such German aircraft technology having a major impact on the Allied air war, and even shifting the advantage to the Axis.