Frankly because in many (not all) places (and especially true the further back you go) -- there's very few good ... anything. When I first moved to Austin TX in 99 I remember being really puzzled by how bad all the food was. Like nearly everything was mediocre. Very slowly better places popped up and everyone talked about them. The one exception was BBQ, and to that end yes -- the "best" was Franklins but frankly it was nearly all very good.
But overtime, other good stuff started to pop up, and eventually there were enough good places that "the best" became less interesting. Still, Austin is far away from NYC, and of the few times I visited Europe (Italy specifically) nearly everywhere in the US is a bit behind. IMHO that's largely b/c of how new everything is. Overtime as areas become more established, things get passed down and around, the quality of everything goes up. And in some places, there's so much good stuff that yeah it makes no sense to talk about best anymore. But for many places the difference between the best and the rest is the decision point of "is it worth going at all?".
But overtime, other good stuff started to pop up, and eventually there were enough good places that "the best" became less interesting. Still, Austin is far away from NYC, and of the few times I visited Europe (Italy specifically) nearly everywhere in the US is a bit behind. IMHO that's largely b/c of how new everything is. Overtime as areas become more established, things get passed down and around, the quality of everything goes up. And in some places, there's so much good stuff that yeah it makes no sense to talk about best anymore. But for many places the difference between the best and the rest is the decision point of "is it worth going at all?".