Separating unrelated concerns is helpful
Separating unrelated concerns is helpful.
Separating related concerns is unhelpful.
Helpful separation:
date.js
auth.js
Dates and auth are unrelated, so separation is helpful.
Unhelpful separation:
User.jsx // just JSX
useUser.js // User.js logic
These are related. The files are fundamentally intertwined, so separation is counter-productive. The *component* is the concern.