I feel that statements like that are a working out of ideas out loud, with a community, and show a thoughtfulness and curiosity that deserves encouraging amongst humans. If you disagree with an idea, show evidence rather than trying to shame people into silence.

The problem with words like depression is that they really do have many meanings.

Depressing yourself is incredibly easy. If you don't believe me try thinking about Global warming, Poverty, War... you get the idea.

It's getting out of depression that's difficult. Otherwise people would go to the doctor to complain that they're not getting depressed enough, wouldn't they? There is such thing as not being sad enough. It's very rare that someone has unipolar mania, but it's common in bipolar disorder to fluctuate between the two extremes.

Maybe it's just mood alteration. It does take a lot of effort.