There are different reasons for this and different leaders can fear this loss for different reasons. Here are two possibilities:
- If the leaders are only concerned with their own power, they may fear that a loss of folk culture will decrease their power. They may get their power from the fact that their family has traditionally had a high status in their culture. For such people, a loss of folk culture would lead to a loss of power.
- If leaders truly care about their people, they may feel that it is a bad thing for them to lose who they are as a people. They may feel that there are good things about their folk cultures (things that are morally good or things that are just important for the sake of tradition). If they think this way, they will not want these good things to be lost as American culture takes over. For example, if your culture emphasizes families taking care of one another, you might think this is good and you might not want that tradition to be lost to the more individualistic American culture.
Having said this, you might want to look in your textbook in case it gives you a specific answer that it wants to see from you.