I understand your point now. If developer will add "Multiplayer" like in last SimCity, compound progression of all cities on a map makes sense. Despite all the flaws that SimCity had, I remember that some levels of intercity trade, citizen sharing and direct communication were quite fun (but I can't remember shared scientific progression tbh). I'm not a fan of forced specialization or cooperation in my city builder, but it's a valid approach.I see what you mean, my idea is just a concept, I didn't go into too much detail. Yes, of course, if a city represent a big whole region map in CSL2, it comes with the problem you've concerned.
I don't know if you played SC5 before. In SC5, each city can have its own specialties or just an ordinary city and they are all connected with each other in the same big whole region map, and if you played a city with university specialization and do the research programs to unlock technologies or something related, it affects to the big whole region map like what you've said, these are defined by country and world advancements, regulations. So you don't have to be worried about to play a tourism-oriented city but can't build something advanced, Plus, CSL use district to act like SC5's one single city. As what said above, what program will affect the whole region or just one tiny city it depends on game developers then.
And yet, there are something you can't achieve if you don't pay. No pay no gain. Otherwise, it lose balance. For example, your tourism-oriented city must have more tourist income than an university city, and your city can achieve more achievement to unlock facilities related to tourism in order to have better experience, these benefits are an university city can't have, vice versa.
Moreover, approach with less simulation and more other forms of fun opens doors to other, less level-headed mechanics. What do you think about zombie-apocalypse? Or superhero DLC in the Worm universe? Or what if your city in non-disclosed eastern European country is being shelled daily? Possibilities are endless...