I personally do not think that tourism is the only cause. Everyone involved in making cultures and traditions commodified all have a part. For example, the locals who welcomed tourism and the government who allowed tourism to affect the city's culture and tradition. Also, there is the advancement of technology. If there is no technology, there would be lesser tourism.
But most of all, we should look into what drives tourism. And the answer would be tourists themselves. We as tourists want to see the world naturally but we do not have the time to watch the world naturally. Therefore, there are staged performances that take lesser of our time to meet our demand and expectation. Tourists also want a better quality experience everytime they visit a tourist destination, therefore there would be developments. All these developments would lead to loss of culture eventually.
Therefore I can say that tourism is a culprit but it would not be the only culprit.