I'm a Specialist Biomedical Scientist in Microbiology. I have previously worked in Biochemistry.
In Microbiology, we consult directly with a team of Consultant Microbiologist's. These are people who have completed med school, gone through all their training and specialised in this field.
In Biochemistry, we never had doctors as part of our laboratory team. We had Clinical Scientist's who would interpret the results and liaise with the ward-based doctors and provide clinical advice.
I can only imagine it's due to the more complex nature of Microbiology. As a Biomedical Scientist, it is definitely more complex working in Microbiology as compared to Biochemistry. You'll find in the NHS that if they can move work to a lower staff grade, they will. Obviously it makes sense as it is cost-saving.
There are Microbiology laboratories that do employ Clinical Scientist's. These aren't that common and tend to be the largest laboratories in each region. Leeds, Sheffield, Newcastle, Manchester etc and it will be a single one who may work more in research. At least that was my experience of the one regional laboratory I have experience of.
So to answer your question, yes some specialities employ less Clinical Scientist's. Microbiology is definitely one of those.