This typology tries to categorize people in 16 different types. Of course it creates prejudices to some extent already by categorizing people into 16 different ways, which shrinks the idea of individuality a bit, by saying that all people have the same "tools" of interacting with or viewing the surroundings etc. The only prejudice here though is that every person can be categorized in one of that 16 types, or in other way explained, that there is no other function than that described in the typology.
You can either use this knowledge of typology theory to learn to understand that there are, if you agree with the typology, in general a set amount of "tools" (the functions), but every individual will use his prefered functions still in an unique way and in different proportions, therefore remains individual. Or you can just create wrong prejudices by saying "Feelers ALL will behave like that and Thinkers will do the exact opposite", then you have the prejudices which probably are meant.
It is like you categorize people in people who smoke and those who don't. Now you can say that smokers see things different than non-smokers (like they wouldn't care about their health or whatever) and therefore make your prejudices. Or you see that there can be several reasons which could lead to being a smoker a non-smoker, and that each may think and behave different still.