Why? If the turrets in these POI can be taken out then things can be set to indestructible or not. Just set the vital parts for the campaign to indestructible. Leave the rest alone. Again, why? As mentioned before Seven Days To Die have "dungeons" but they have done the sensible thing and given the player the option to take that route or not. You can break down walls and still get to the loot you need to find for the quest. This is good game play. Restricting the way people may want to play isn't good game play.