Because pits are most depicted as monsters, demons, vicious beasts attacking children and beloved pets... When really.. it is the owner's fault... Or sometimes the breeder's... if the pup had a dis-temper from birth - as I have seen with a german shepherd who was badly...badly bred...
I don't have a preference for what type of pit I like, just as long as they are friendly lol.
Breed for the breed, not for the money; the words any REAL breeder would understand.
You must know nothing in order to know all, for all is nothing and nothing is for all.