why does the standard let me free-store allocate classes without constructors?

If you have a class without a destructor:

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

The standard does not let me "locally" allocate an instance of that class:

int main()
{
    A a; //error
}

But it seems like it is ok if I allocate that on free-store:

int main()
{
    a *p = new A();
}

As long as I dont call delete on that pointer:

int main()
{
    a *p = new A();
    delete p; //error
}

So my question is, why does the standard let me have a class without a destructor if I allocate it on free-store? I would guess there are some use cases for that? But what exactly?