Thank you so much for your thoughts! I completely agree that another person shouldn't have the power to label you. I also believe it has a lot to do with one of the Four Agreements. If you've never read into it I think you'd be fascinated by it! The one I think this connects with is basically about making Word into your Truth. If something you think is confirmed by even one other person this becomes your truth and you build your opinions and ultimately your life around that truth.
For example, say you're young and you sing for your parents, one tells you you're great and the other tells you that you aren't. If you decide to follow the opinion that you're great it will cause you to sing more, believe you can be famous one day, take the needed steps to improve because you believe you can be great. Or you can believe that you aren't great, this becomes your truth, and you never sing again and tell confirm that you are not. This is a rough analogy, but it's such a huge idea it's difficult to sum up in a comment, but I hope you see where I'm coming from with that!
I think a doctor confirming that you "have depression" justifies your emotions and gives you an excuse to continue on and hope someone else can make you "better."