At some point you'd just want to get past describing the problem though, and when it comes to solutions meds and therapy are of course just general answers. Few of us will have the background to look at the medical aspect in detail (although general lifestyle considerations are not a bad idea to cover all bases) but when it comes to the therapy side we can all look at how we think, and even if we have limited psychological knowledge it always helps to have another perspective when we're too embedded in the current mind state, not to mention support.
When it comes to depression it does seem to have to do with a sense of loss. It's certainly a loss of interest in life, and what does an organization like WTS say about life? Even though there's this "hope" of living forever on earth so it's a little bit easier to relate to than heaven or some other form of afterlife, it is still something in the future - and there is no guarantee that one will attain it. Added to that lots of normal life activities are restricted, it's no wonder that it becomes an internal state when you have those influences. Peoples identities are formed around the work or function in the organization, whether it's a position of oversight for men or putting in lots of hours as a pioneer for women. This is not a natural identity for people.