I disagree. In two of the sectors that I'm familiar with (travel and electronics), there are a number of huge players that have thousands (millions?) of keyword-driven, computer-generated stub pages containing nothing but "Add a review," some ads, and maybe some price-comparison links. If such pages are merely ignored by Google and other SEs, the sites have no incentive to refrain from spitting out stub pages for every conceivable keyword. What's more, the success of their spit-out-a-million-stubs approach just encourages every Tom, Dick, and Harry to try the same strategy. A "quality score" that took the ratio of real pages to stub pages into account would discourage such "If it's Tuesday, let's spit out a million empty pages about Belgium" shenanigans.