This is the error though. The math is not actually simple, unless you use the simplistic assumptions that have since been proven incorrect. The article mentions how they eliminate externalities like differing factors of growth as well. They compare locations with higher minimums against similar locations without. Like 2 nearby cities in different states. There have been literally hundreds of studies like this in the US alone, which is why the conclusions are so strong. 

FYI, most conclude that point 1) is exactly what happens. Resulting in a shift of wealth to those receiving minimum wage, just as it's supposed to do. There is conjecture that minimum wages may impede future job growth. ie it raises barriers to entry for new firms. But it's pretty conclusive that it has no measurable effect on overall levels of employment at the time of the raise.