As far as I understand it, microevolution and macroevolution differ only in time and scale. It's kind of silly to say one exists but the other doesn't when there is very little distinction between the two.
There are some caveats there. For macro evolution to be successful, every in between micro evolution step has to be profitable for the species, or at the very least not harm it. There are actually some very weird constructions in animals because of this constraint. If I remember correctly, the channel that connects the air-intake on the back of a whale was an example of that. It runs from his back forward to his mouth, then backward to the lungs, because it was originally connected to the mouth.
