It's not just small towns they ruin, they've done precisely the same to cities, only it happened so long back that most people aren't aware it used to be any different.
The big supermarket used to be a place you went if 1, you had a big car and could carry bulk, 2, the sheer novelty factor, once in a while, for a change, 3, the rare occasion when you couldn't actually find what you wanted in a local shop, local shops that in most cases were actually cheaper than the supermarket.
This is not that long ago in the grand scheme of things, it was still like this in the late 80s and into the early 90s, then more and more people started driving, shopping became about convenience and little else, the small shops vanished over the space of a couple of years, often because they had elderly owners and upon retirement nobody wanted to take the business on.
I think it's lamentable, not just because of romantic notions of local business or sentimentality, I can not find fresh fruit and veg in any supermarket that matches up to the quality, taste, or longevity of greengrocer produce, and given that I live in a city centre, farmer's produce and market stuff is not readily accessible, so I do not eat anywhere near as much fruit and veg as I once did because supermarket stuff is largely crap IMO.