I've done a fair amount of research regarding the allocation of resources during the war, and the introduction of the North Africa campaign strained resources in more critical European fronts. How significant was this strain, and were there any other aspects of the North African campaign that adversely affected the outcome of World War two?
Starting with Operation Torch, the American Armed Forces would have been far less successful, even reaching failure in an invasion if continental Europe anywhere without the experience they gained in North Africa due to Operation Torch. The American Army had very little experience with combat of the kind that would be fought in Europe, as it was very different to the Pacific, and anyhow the Germans were an altogether different foe. The American forces very much needed to learn how to fight differently, and the lessons learned in the deserts of Algeria and Tunisia were to be very important in the future.
On the other hand, it also introduced some early tension between the British and Americans. The British 8th army had been fighting in North Africa for a long time, and some units had been stationed there for up to 3 years fighting the Italians, as Mussolini entered the war in June 1943. The British had already gained experience from this campaign, and took it upon themselves to help teach the Americans the lessons of war. However, British officers often had a certain way of doing this, which came across to the Americans as condescending, which it very well may have been. This meant that the Americans had to learn the lessons the hard way.
Therefore it could potentially be considered a turning point because it meant that the Americans were able to be a more effective fighting force with more experienced troops and commanders, as well as more developed tactics and strategies.
The North African campaign was a considerable strain on British Resources for 3 years of the war, but in the end meant that an invasion of Sicily, Operation Husky, was possible, followed by an invasion of mainland Italy. While the 'soft underbelly' of the Axis as Churchill so confidently proclaimed it to be, was a strain on resources, and didn't bring about the fall of Germany as he thought, it meant in the end that valuable lessons vital to D-day were learnt.
However, it could be argued that a battle like Stalingrad that was a huge defeat the German Wehrmacht might have been more significant.
Sources:
The Second World War - Antony Beevor
Fortress Malta - James Holland