Using a specialization of variadic template as a template argument

Consider the following:

template <class...>
struct MyT;

template <class T>
struct MyT<T> {};

template <template <class> class TT = MyT> struct A {}; // fine

using B = A<MyT>; // does not compile

int main() {
  return 0;
}

When MyT is used as a default argument of A, the compiler (g++ 5.4.0) is happy. However, when it is used to instantiate A, the story is different:

temp.cpp:19:16: error: type/value mismatch at argument 1 in template parameter list for ‘template<template<class> class TT> struct A’
 using B = A<MyT>;
                ^
temp.cpp:19:16: note:   expected a template of type ‘template<class> class TT’, got ‘template<class ...> struct MyT’

I can fix it by introducing an alias:

template <class T>
using MyTT = MyT<T>;

using B = A<MyTT>; // fine

The question: what is the reason for the error and is there a solution without introducing an alias?

EDIT Please note that A is declared to have a template template parameter as shown and that is not given for change.