I am not at all sure what “Oralists” are advocating, since there are quite a few divergent views. I’m not involved in child education.
HOWEVER I will hazard a reply that from my observation and experience the central argument of oralism is that deafness does not preclude learning to speak intelligibly and learning to lipread/speechread sufficiently to understand speech. Naturally the individual ability in both areas will vary, depending on both native aptitudes and practice, degree of hearing loss and age of onset of hearing loss.
Leaving out politics and emotionalism, the question is CAN deaf people learn to speak clearly? CAN “most” deaf people learn to lipread adequately to understand speakers under ideal conditions (and with repetition).
Further, Since the evidence is that SOME deaf people can do both of the above (and very well, too!), should the education and therapy systems attempt to teach both speaking and speech reading skills to ALL deaf people?
If not all deaf people are capable of learning speech skills, (which of course are very difficult to learn and master without hearing) then WHAT criteria will be used to decide which deaf people (presuming children) will be taught with speech training and which will be taught in sign only?