Because if that stuff helps them they do not have depression, but they are experiencing sadness. They are not the same but everyone in this thread is treating it the same.
Your source does not support your claim ("if that stuff helps them they do not have depression"). In fact, it contradicts your claim since it says "Lifestyle changes can also help you feel better if you’re experiencing depression."
We should not be pathologizing sadness.
https://www.healthline.com/health/depression/depression-vs-s...