I like Golarion's weird 14-16th century setting with a random steampunk area hidden from everyone else. It's a little bit of everything, just like IRL Earth.
The idea that Golarion has any sort of reference period at all is laughable, or indeed that it has any sort of consistency. It's a bunch of poorly worked out mini-settings, each with a gimmick but little else, randomly placed next to each other on a map with no rhyme or reason. While Faerun at least
tries to depict a general cultural history, how peoples and nations came to the place they are now and how they interact with each other. It get things wrong, but at least it tries, and that shows. Still a bit too "kitchen sink", but oh well, that seems to be the norm with DnD and its knockoffs...
The "general store" thing is mostly a RAW conceit, if you go back and look at when they used to do REALLY detailed towns (see the old Volo's guides) there'd mostly be specialists, and maybe one guy who acts as an agent for one or more merchant concerns. And that one guy is less a "general store" and more a "exotic goods and/or stuff not obtainable locally" guy.
Well, that is just one aspect (though I would argue that even then, the "historical" way to buy things would be to go to guild streets and buy directly from craftsmen, who all have identical prices and are in the same part of the town because guilds). But also, like, everything else.
Faerun (especially in the Heartlands which have become, like,
the Forgotten Realms setting with everything else sort of, well, forgotten) has a lot of random self-governing towns randomly placed in the wilderness. Why is the town exactly there? Why are there not further villages around it, where the soil is probably just as good? Now, if you imagine a mining boom town which of course springs up at exactly the ore deposit, that makes sense. And why is it self-governing? Why are there no, well, actual
Realms in most of the "Forgotten Realms", again, especially not in the Heartlands? Again, images of the lawless frontier town. Etc etc.
Indeed, I have been reading FR sourcebooks lately, and the 2e Player's Guide to the Forgotten Realms even says that it is much like the 12th/13th centuries, and that
as such, there are not many nations yet, just city states and the like - when of course, in truth it was the exact opposite way. You didn't have states, true - you didn't have a governing apparatus as such. But you did have realms, as the domains of individual rule, that spanned vast areas - especially the poorly settled areas. Indeed, where you would have city states would be the better developed parts of the continent, like Italy. So, yeah, the sign of "primitive times" was exactly you had large realms with feudal structures and not much in the way of governmental institutions. Meanwhile Forgotten Realms has city-states with little territory but indeed governmantal institutions, and tries to sell that as a mark of medieval times. It's ass-backwards.