Yes, my own experiences with depression in those around me (thankfully not in myself) have left me seeing no way in which depression provides benefits. It is a terrible debilitating disease (or symptom, or whatever it is) that literally saps people of their will to do anything regardless of external stimuli. I find it very hard to imagine something so maladaptive being presented as possibly useful.
I would guess that sentiments like this are the main reason behind the powerful response to your thread. It is almost like claiming that "there is a reason for cancer".
Edit: I would also note that it's possible that we're simply talking past each other, as the term "depression" actually covers some quite different disorders; it's possible that what you're thinking of when you use this word is different from what I'm thinking of - to me, it mostly refers to a disorder where people feel either deeply sad or deeply anxious, but either way they are lacking almost entirely in motivation, finding it hard to even get out of bed sometimes; and all this with little relation to external stimuli.