It seems that the authors are simply trying to point out that use of the 4C model is not common and that other methods are normally used.
There is no description of the race and ethnic composition of the sample. I am not well-versed in the ethnic composition of Mexico, however, would it be helpful to know the degree of representation of, for example, youth who are Black, of Indigenous ancestry, and of European ancestry? Or are there other ethnic or cultural groups that should be represented?