I think she was referring to the fact that Chihuahuas do have specific quirks and traits that make them a fairly unique breed.FWIW, I don't think that not liking strangers is "letting the breed be." Like any dog it is just in how it is initially raised; doesn't mean that by not socializing the majority that by nature they are like that. I know a LOT of chi's who love meeting hew people and are friendly. Just throwing that out there; as I don't think that proper socialization (which should be done for any dog really) is changing the breed at all.
My male dog is very well socialized and he will go to anyone I expose him to, but you can tell he is just tolerating it because he has been taught to/well exposed.. he does not really enjoy being with people other than "his" people.
However his behaviour is stellar in those situations but he is not affectionate towards people that are not his and he is not really that interested in the people.. he just deals, I have found this to be more common than not with this breed and I have plenty of experience at this point, that in my opinion is the difference between a well adapted Chihuahua & a poorly bred lap shark (and yes I've owned those as well)