> I prefer what I do with Python in this regard: The IDE shows me unused variables, I can run my code with them, but I can't commit since the linting hook will produce a hard error at commit-time if something's wrong.

The problem is that while you do that, essentially no-one else on the planet does — and anyone who uses a library thus has to deal with the fact that that library has approximately a 100% chance of having nits like unused variables.