From [dcl.init.general/7] (bold emphasis mine):

To default-initialize an object of type T means:

• If T is a (possibly cv-qualified) class type ([class]), constructors are considered. The applicable constructors are enumerated ([over.match.ctor]), and the best one for the initializer () is chosen through overload resolution ([over.match]). The constructor thus selected is called, with an empty argument list, to initialize the object.
• If T is an array type, each element is default-initialized.
• Otherwise, no initialization is performed.

How can a scalar object be at the same time default-initialized and not initialized?

For instance consider this program:

int main() {
    int i;
    return 0;
}

From [dcl.init.general/11]:

If no initializer is specified for an object, the object is default-initialized.

So i is default-initialized.

From [basic.life/1]:

A variable is said to have vacuous initialization if it is default-initialized and, if it is of class type or a (possibly multi-dimensional) array thereof, that class type has a trivial default constructor. The lifetime of an object of type T begins when:

• storage with the proper alignment and size for type T is obtained, and
• its initialization (if any) is complete (including vacuous initialization) ([dcl.init]),

So i is a vacuous initialization and therefore its lifetime begins. Yet i is uninitialized so its lifetime does not begin.

Therefore I suggest we reword [dcl.init.general/7] from

• Otherwise, no initialization is performed.

to

• Otherwise, nothing is performed.

That way scalar types are not in two different states at the same time.

Same remark for [dcl.init.general/6] (bold emphasis mine):

To zero-initialize an object or reference of type T means:

• if T is a scalar type, the object is initialized to the value obtained by converting the integer literal 0 (zero) to T;86
• if T is a (possibly cv-qualified) non-union class type, its padding bits are initialized to zero bits and each non-static data member, each non-virtual base class subobject, and, if the object is not a base class subobject, each virtual base class subobject is zero-initialized;
• if T is a (possibly cv-qualified) union type, its padding bits are initialized to zero bits and the object's first non-static named data member is zero-initialized;
• if T is an array type, each element is zero-initialized;
• if T is a reference type, no initialization is performed.

How can a reference be at the same time zero-initialized and not initialized?

Therefore I suggest we reword [dcl.init.general/6] from

• if T is a reference type, no initialization is performed.

to

• if T is a reference type, nothing is performed.