Changing the 'this' variable of value types

Apparently you can change the this value from anywhere in your struct (but not in classes):

struct Point
{
    public Point(int x, int y)
    {
        this = new Point();
        X = x; Y = y;
    }
    int X; int Y;
}

I've neither seen this before nor ever needed it. Why would one ever want to do that? Eric Lippert reminds us that a feature must be justified to be implemented. What great use case could justify this? Are there any scenarios where this is invaluable? I couldn't find any documentation on it¹.

Also, for calling constructors there is already a better known alternative syntax, so this feature is sometimes redundant:

public Point(int x, int y)
    : this()
{
    X = x; Y = y;
}

_{I found this feature in an example in Jeffrey Richter's CLR via C# 4th edition.
1) Apparently it is in the C# specification.}