Pretty meaningless results I reckon. The forces used to test are way in excess of any likely to be found in practical applications. In the illustration it is the wood that has failed - not the joint. The force has been applied in one direction only - in use a dovetail is required to withstand multidirectional forces.
Skinny dovetails are definitely WEAKER than fat ones, and can sometimes be seen failing in older drawers, especially when taken to extremes.
But (as those tests document, and Kirby points out) dovetails are capable of overkill strength for many applications, leaving the design envelope wide enough for artistic considerations to be included as well as structural ones.