It's kind of funny how many non-Italian things go into making that distinctly Italian food, pizza. I don't think of this as a criticism, but a credit to them, that they will unashamedly take those things they can't find or weren't originally found in their region and make them their own.
Just remember, it takes exploring half the world to make a Hawaiian pizza.
What better way to grasp the impact of an activity than by doing it? Of course this can be harmful - if every visitor to a natural reserve picked a flower, eventually that reserve would have no more flowers. But it can certainly bring that impact home when you're in the midst of the results of many insignificant actions.