Yes, the use of local norms limits the benefit of research results, because with local norms, people just do whatever they want to do. This is true even if the local rule is shown to now be as good as the national rule. People just do what they want to do, regardless of what is better or used regionally or nationally.
I do not believe local norms should be considered in research, it certainly shouldn't be seen as a benefit. I think the use of local norms in research could skew results and provide unfounded results that wouldn't exist otherwise. Local norms support stereotypes that don't hold up against the actual community they are applied to.
The use of local norms should not limit the benefit of research results that may come about out of the United States of America or the rest of the world as well. These benefits could help a number of different people we should respect the choices that the people want.
Local norms are useful for making predictions based on disparate data. For example, if you were examining test scores for students in Scarsdale, NY (America's richest school district) and Barbourville, KY (America's poorest school district) you would find that almost all of the Scarsdale students performed better than even the top scoring Barbourville students. The only way to truly measure these students performances against one another is to eliminate the variable of wealth. Local norms provide a way to do this.