Fair point - if those exist. Current tourist traps are popular because those are the very-interesting and somewhat-interesting spots, as opposed to "there also

Fair point - if those exist. Current tourist traps are popular because those are the very-interesting and somewhat-interesting spots, as opposed to "there also used to be a medieval city here, now there's a factory, gee that's interesting". In other words, that's already happening, and it does help, but doesn't scale quite with the demand. There's always diversification ("go see that niche thing if you're into it - old mine, train museum, festival of this and that, power plant, take a bike tour instead"), but the attraction of extremely-popular spots is self-reinforcing.