I mean the other point is that neither May nor Cameron had any authority to do what they promised. Cameron said that he would trigger the A50 notification instantly the result was known, but we then learned that he would have been constitutionally forbidden from doing so, had he tried; Theresa May's constant promise that we would leave on March 29th, too, was not within her powers to assure, depending as it does both on the intentions of Parliament and on the EU.
Not that this absolves them of any blame, because then the sin is to make implies promises that, surely, they must have known, or been advised that, it would be impossible to keep.