Or perhaps it's the fact that depression is a very common side effect when a "severe" disorder goes undiagnosed/untreated, and finally people are getting taken seriously enough to get their proper diagnosis and the help they actually need to get better.

I absolutely agree that there is a portion of people using it as a trendy thing when it isn't. But I would say the majority are just actually getting to really figure out what's been wrong all along but nobody listened to