> Often the individual suffering is fundamentally unaware of their own circumstances. I didn't realize how messed up my family relationships were growing up until much later. There are various reasons for this unawareness, but I believe the depression/anxiety are there to force our conscious self and the people around us to acknowledge that something is wrong.
If a situation is causing no problems outside of depression/anxiety, and you took away the depression/anxiety mechanism, there would be nothing wrong with it.
If there are other problems, then piling depression on top makes it harder to fix.
A lot of medical conditions cause chronic pain. The pain helpfully signals "something is wrong" once, and then keeps unhelpfully reminding over and over. You want to treat the pain itself in that situation. Sometimes the pain is the only thing you need to treat at all.
Being an indicator of other problems does not make chronic pain useful. Depression is similarly crippling and unhelpful.