Why do linked lists use pointers instead of storing nodes inside of nodes

It's not just better, it's the only possible way.

If you stored a Node object inside itself, what would sizeof(Node) be? It would be sizeof(int) + sizeof(Node), which would be equal to sizeof(int) + (sizeof(int) + sizeof(Node)), which would be equal to sizeof(int) + (sizeof(int) + (sizeof(int) + sizeof(Node))), etc. to infinity.

An object like that can't exist. It's impossible.

C++ is not Java. When you write

Node m_next;

in Java, that is the same as writing

Node* m_next;

in C++. In Java, the pointer is implicit, in C++ it is explicit. If you write

Node m_next;

in C++, you put an instance of Node right there inside the object that you are defining. It is always there and cannot be omitted, it cannot be allocated with new and it cannot be removed. This effect is impossible to achieve in Java, and it is totally different from what Java does with the same syntax.

In Java

Node m_node

stores a pointer to another node. You don't have a choice about it. In C++

Node *m_node

means the same thing. The difference is that in C++ you can actually store the object as opposed to a pointer to it. That's why you have to say you want a pointer. In C++:

Node m_node

means store the node right here (and that clearly can't work for a list - you end up with a recursively defined structure).