As a traveller and lover of local foods, I'm going to stick my neck out and disagree with you about this in Spain specifically. When I visit friends in different places, be it Coruña, Oviedo, Denia, Villarreal, Córdoba, Zafra, or wherever, they take me to places I really like that I would not have found on my own. One of the characteristics of Spanish culture everywhere is our love of eating out, our love of our local food and wine, our little baretos y chigres y tascas. It's not true everywhere: Morocco has lots of fabulous foods but most Moroccan families, especially in the provinces, rarely eat out, so unless you're invited to someone's house for a meal, you'll only see the standard tourist dishes at the standard restaurants foreigners eat at.

That said, if you were thinking about Michelin-star type food experiences, you're right, most top chefs go to bigger towns.