Europe is full of historic walkable towns, mostly the smaller / less central ones because capitals and important cities have been heavily changed aftere cars took over. But many still have at least a walkable central part. Last weekend I spent in Banska Stiavnica, a former important mining town in central Slovakia, and that is an example of such a town, as would be the centre of Cordoba in Spain, which was very important and then ceased to be, and so on. So the issue is, I think, more of marketing: the popular walkable destinations are overcrowded, but there are many like it, maybe without all those palaces but still beautiful and much much more quiet.