Is the point that any var declared in between the braces automatically goes out of scope, to minimize potential duplication of var names and unintended behavior ?

The worst I've seen is old school C programmers who insisted on reusing loop variables in other loops. Even worse, those loop variables were declared inside the loop declaration, which old C standards allowed to visible outside of it.

So they would have stuff like this

  for(int i=0; i<10; i++) { ... }
  for (;i<20;i++) { ... } 

Later versions of C++ disallowed this, which led to some interesting compile failures, which led to insistence of the old stubborn programmers that new compilers simply not be used

Now you have to make `f` nullable and you run the risk of not initialising it and getting a null pointer.

You can't do it in C, but in functional style languages you can do this:

  let f = {
    let bar = ...;
    let baz = ...;
    let barbaz = ...;
    barbaz
  };

Which is a lot nicer. But if you ask me it's just a function by another name except it still doesn't limit scope quite as precisely as a function.