We all have examples of places that have been "invaded" by tourists. Even in a small country like Portugal, in recent years, I was surprised to learn that Lisbon and Porto are now leading places to visit, they are there at the top of the destinations "one must see". These are fashions, and I have no doubt that they will be replaced by other destinations in the near future. One place I go to very often, the southwest coast, is still a haven (apart from the summer months) of quiet; I used to vacation there with my parents 40 years ago, when there was no running water or electricity.
Recently I spent 5 days in London with my family, doing the habitual site seeing, museums, etc. The place was packed, as usual. There was even a queue in Greenwich for the meridian picture...
Iceland... never been there. But really, how can photographers go to those places, publish the photos, and then expect such places to remain undisclosed to the greater masses? It is illogical.