It’s not a “no you can’t” just because you know of some exceptions.
And even then, they are still correct while you are not. You can copy the GET url even if it ultimately it requires authentication in a way that you can’t do it all for a POST request.
Typical scenario is to redirect to login and after successful authentication return back to the requested URL, so the method doesn’t fail if server is implemented correctly.
no, you cant. if the server requires any headers such as Authorization or Cookie, this method will fail.