ASK: What is the fundamental nature of a login page?

Is a login page a first-order feature of a site, a real piece of functionality that should have its own url (aka `/login`)? Or..... Is a login page one possible view state of an "actual" page? For example, if you have a secret dashboard page at `/secret-dashboard`, and Bob is logged in he would see his dashboard data, while if Suzy was logged in she would see different data (aka a different view) customized for her. Doesn't it follow that a non-logged-in user would simply be presented their "data", which in this case would be no data at all and the login form instead? All while the url stays at `/secret-dashboard`.