Why do most websites use the pair of username and password as we can just use a long password like a token to identify a user?
A simple example: On the server, we create a JSON file with user data inside of it (email, role etc.) and give it a random 32-characters name. Then if a user wants to log in, he just copy/paste his long password into one form input and submits the form. If submitted password matches with the name of JSON file on the server, the authorization is successful and the server identifies the user.
So why not and why username and password?