As a regular traveller for leisure and living in a major tourist destination (Amsterdam), I've been thinking and experiencing a lot the issue of over-tourism. However, I disagree with the article's idea that the only solution is to stop traveling voluntarily.

Personally, I think pre-approved tourist visas will be the most efficient way of controlling how many people can travel to a country and then regions of a country. So, the solution already exists in part. Understandably, a few cities and areas of a country receive most tourists. You could therefore regulate the amount of visitors in each area by issuing location-depdendent visas. For example: "On the chosen dates you can come to the United States, but cannot visit New York or Florida. You may visit California, Nevada, Georgia etc etc."

It's terrifying and limiting, but realistically it's the only pro-active solution I can think of to improve the sustainability of a place, especially for the locals. Flight prices are likely to continue to drop and more people will have means to travel internationally. You cannot count on people's consciousness to address this issue.