So how is it better than C where you get a warning (at least from GCC) that you have unused variables? You can quickly test things and you are coming back to fix all the warnings later anyway.
It's not as easy to do with a compiled language, of course, but I don't think it would be over the top to have the compiler exit with a non-success code if there are warnings when building.
The "warning fatigue" you get from C is because the warnings are either about false positives or about things that are too trivial to bother with, not because of a property inherent in compiler warnings themselves.
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.