It is true, and that is becoming increasingly the case. I, for one, am from the old school. I have been an occupational therapist for a long time. When I started practising this profession, many of the occupational therapists available worked with outpatients. We rarely see that today. Occupational therapists who work in hospitals are strictly assigned to in-hospital patients.
Indirectly, a medical referral is necessary in a hospital. However, things are different in such settings as schools, where occupational therapists have a private practice. Only hospitals, internally, require a medical referral.