What is the use case for var in ES6?

Question

If the let keyword introduces a proper implementation of block scope, does var any longer have a use case? I am looking at this from a software des

Answer 1

let can't be used in global scope yet. var can.

This is what you get from Chrome when you try a global let outside of strict mode:

Block-scoped declarations (let, const, function, class) not yet supported outside strict mode