Just as an example. You are gay. You live in a gay friendly place. Until one day, a new government takes office that will incarcerate gay people. They now have access to every one's phones who previously had nothing to hide.
For the same reason you close the door when you are pooping on the toilet. You know what you are doing there, I know what you are doing there, so leave the door open.
That's what I always lead with, if we come into that territory :)