We first started studying heart disease because we noticed that a lot of people died from heart failure. We've since learned of the myriad of different heart diseases and study them in detail, resulting in huge strides in treatments. Same goes for cancer: we now know of more strains and types of cancer even on a single organ, but you gotta start somewhere. Similarly, we have a huge number of Americans dying from guns, and we have no idea why because we're somehow not allowed to study that in depth. I'm sure we can refine that target somewhere down the line but right now all we could do is guess, which is not sound science.