That was my first thought as well. If you keep mutable variables function-scoped, I see no difference between:

    // We do this:
    let point = Point { x: 2, y: 4 };
    let point = Point { x: 4, ...point };

and

    let point = Point { x: 2, y: 4 };
    point.x = 4;

And that's generally what the problem is with mutable variables. You either erroneously assume `x == 2`, or have to read all the code between assignment and the point you're trying to change something.

Immutability gives you less thinking and parsing overhead. This kind of defeats that purpose.