To give a short and sweet answer: sabermetrics is also about scoring runs, they simply analyze in the aggregate to counter "old housewives' tales". No one is trying to say that sac flies don't matter. As sabermetrics advance, they don't counteract every "old school" baseball theory, in fact they reaffirm some of them such as pitch framing. But there are many old, bad ideas in baseball. And sabr tries to move past some of those bad ideas. One of those bad ideas was that walks are both the fault of the pitcher and are relatively worthless from an offensive standpoint.