This setting is found on the Profile > System > Settings page, and it answers the question of "What should someone be able to do with a goal if they don't have special access or ownership of it?"

Using this setting, we can decide whether non-contributors (non-owners) should be able to add Updates, Comments, Tasks, or Risks to goals. Typically, only Comments are allowed.

Between this setting and the Access Controls available in the Strategy Model, we are able to highly customize the goal management experience across all users.