Even if the critique suggests "the memories may be false or distorted" the essence still holds properties in how the person has been modified by it. I would still consider the person suffering from trauma associated to it. Trauma from misinterpretation is just as real in comparison to trauma from an event that did in fact happen. Both may result in a person being altered negatively.
What I'm saying is that your theory - "I believe past trauma is the root cause and I doubt people have depression if they haven't had some type of experience they would classify as trauma" was proven false in the study I cited.
It found that one in four depression sufferers had no childhood trauma to speak of.
Your (apparent?) explanation for this - that 1 in 4 depression suffers have simply suppressed their trauma memories - has no scientific basis.
It all gives the appearance that you're projecting your own personal experience without providing evidence.
I don't consider the study proving anything false.
If a person has no childhood trauma to speak of, it can be instilled in the subconscious and they're unable to process it. Psychology is built upon theories with little scientific basis of replicating the assertions. Observation is really all of psychology studies.
Simply, it's difficult or even impossible to provide evidence around problems surrounding the psych by what you're asking. Nobody can assert with science to how conscience is even real.