Why did the schieffen plan fail?

After World War I, some historians have launched the idea that the Schlieffen Plan in its earlier, radical form accurately predicted the war situation, and if the German High Command scrupulously kept his assumptions, the Central Powers would gain an advantage in Europe, beating France, which would lead to their victory in World War I. According to this reasoning, the German staff made a mistake by adopting a more conservative variant. Today, historians say that the German plan in whatever form he had little chance of success, because the slow-moving armies of this period were not able to do so ambitious maneuvers without losing its impact force.