players joining instances uninvited

The absolute worste thing ive ever seen in any game anywhere. Friends list or not, if i dont make my game public, nobody should be able to join my instances unless i invite them. I have a friend im not trying to block as i play endgame with him, but ive told him 100 times to not join my instance unless i party invite him. PLEASE REMOVE THIS FEATURE. I DO NOT WANT ANYONE IN MY INSTANCE UNLESS INVITED. absolute garbage idea to have that. he kills everything and ruins my tests and exp. worste experience ever.