You are making a point that shares much with Foucault’s work: trying to understand why and how fields like psychology and sociology came to be crystallized into academic pigeonholes. Your frustration is what he studied.

If you want a deeper answer to your question read:

R. Rorty (1991) “Moral Identity and Private Autonomy: The Case of Foucault” (in Essays on Heidegger and Others)

Rorty makes the point that there are (at least) two ways to read Foucault: both interesting and also in tension.