A friend class can access private and protected members of other classes in which it is declared as a friend. It is sometimes useful to allow a particular class to access private and protected members of other classes. For example, a LinkedList class may be allowed to access private members of Node.
Friend Class and Function in C++ - GeeksforGeeks
This feature could become pretty userful if we could be able to take advantage of it in blueprints and plenty of friends of mine myself included would love to see it.
Friendship is one of big features that are part of OOP design after all!
- Thanks!