Because `this auto&&` was not introduced to allow for recursive lambads. That's just a happy (though not very interesting) side effect. It was introduced so that you don't have to write duplicated code such as:

    class Awesome {
        // ...
        foo& my_method() { /* ... */ }    
        const foo& my_method() const { /* ... */ }
    };

and the extra duplication for lvalues and rvalues.