But when we look at depression diagnosed by experts we see a variety of forms, and a variety of strengths.
I agree that well meaning people sometimes offer really bad advice.
But advice about developing a healthy lifestyle (being careful with caffeine, alcohol, recreational drugs; eating better; sorting out sleep; getting exercise) and developing a social life are important, because these thing help people with very serious, life threatening, illness. In combination with therapy they can be part of an effective cure for many people. (At least leaving others with several years of recovery). If needed, this advice can be combined with medication. And, if needed, all of this stuff can be started if the patient is in hospital. (At least in England all MH hospitals should have programmes of OT to start social life outside hospital and they should have some kind of exercise stuff, and contacts with local gyms.)
I've known people who are ill enough to require electro convulsive therapy and they said that this other stuff was important to them, but that they needed help to apply it.
And that's the important thing. Saying "I am to ill to do this stuff" is not the same as saying "this stuff would not be helpful to me if I did it". What people need is help to apply this stuff.