Stu,
If I understand you aright, I'm saying that our use of "his" leads us to assume so often that the person is a man, when it might be a woman.

Thus we get the familiar scenario of, for example, the nurse saying to the patient,"The doctor ios just coming", and the patiuent being TAKEN ABACK when a woman walks in.

In better words, constantly saying "he", where "they" works, leads us into expectations unfair (to say the least) to women.

Best wishes

Ivor