API POSTfull

In my high school had programming classes, not so properly to learn something, them the programming teacher, only told the less than basic about REST API, to operate with databases. This way, i saw a new and simple way to solve the problem with REST, the way was use only post.
I saw problems, with get, pass params in the path, was very insecurity. And i wasn't to expose the php file so directly, and wasn't create multiple endpoint, then edits them.
A Example Below:

 $data = json_decode(file_get_contents("php://input"), true) ?? $_POST;
    if(isset($data['Operation'])){ 
        $WhoOperation = $data['Operation'];
        $content = $data['Content'];

        switch ($WhoOperation) {
            case 'select':
                SelectAllEmpresas($conn);
                break;
            case 'VerifyAccount':
                getUser($conn, $content);
                break;
            case 'selectUsers': 
                SelectUser($conn,$content);
                break;
            case 'addUser':
                addUser($conn,$content);
                break;
            case 'deleteUser':
                deleteUser($conn,$content);
                break;
            case 'alterUser':
                alterUser($conn,$content);
                break;  
            default:
                error404();
        }
    }else{
        error404();
    }

Above, had all the operations of an CRUD, only with posts. Only when i learned more about API, and discussing with friends, i named it POSTfull. It's a predecessor of GraphQL, i think, actually. I was very funny this code today.