Final answer:
Excessive commercial development in tourism can diminish regional landscape distinctiveness.
Step-by-step explanation:
Tourism can diminish regional landscape distinctiveness through excessive commercial development. When tourism focuses on maximizing profits and catering to mass tourism, it often leads to the construction of large resorts, hotels, and other tourist facilities that can alter the natural landscape and disrupt the local ecosystems. For example, the construction of high-rise hotels or amusement parks can change the skyline and natural beauty of a region, diminishing its distinctiveness.