Just to be clear we're not trivializing the condition, you're right that some sufferers of depression don't really need a qualified person (particularly if they have a good support network and sufficient strength of mind) but some people only turn around after CBT, for example.
I do agree with the general thesis that talking to someone willing to listen has a neutral to positive effect. I'd also suggest it's especially helpful for people who feel they can't or shouldn't talk to anyone else they know about it.