What is the point of deleted destructor?

Question

I come across the rule (section N3797::12.8/11 [class.copy])

An implicitly-declared copy/move constructor is an inline public member of

Answer 1

The rationale for that bullet is covered in defect report 1191: Deleted subobject destructors and implicitly-defined constructors which says:

Consider the following example:

struct A {
   A();
   ~A() = delete;
};

struct B: A { };
B* b = new B;

Under the current rules, B() is not deleted, but is ill-formed because it calls the deleted ~A::A() if it exits via an exception after the completion of the construction of A. A deleted subobject destructor should be added to the list of reasons for implicit deletion in 12.1 [class.ctor] and 12.8 [class.copy].

and the proposed resolution was to add the bullet you note above and the same wording to the following section 12.1 [class.ctor] paragraph 5:

any direct or virtual base class or non-static data member has a type with a destructor that is deleted or inaccessible from the defaulted default constructor.