Not sure about anyone else but I think your title is downright silly. "True Cause" implies that one idea or line of thought process would cover ALL CDers of every variety. Surely you did not mean that?
ANYone here that actually takes the time to READ Qs and responses knows there are many reasons WHY. It's not Rocket Science.
People who bother to READ know at least ONE piece of the puzzle. Very few deny "it" in numerous threads. It's the ONE THING that binds most here regardless of any letter groups they might wish to put themselves in and it's not difficult to imagine exactly where the shame and guilt that so many here have, comes from.
There is plenty of information "out there" on the net as well as can be found at libraries but few people will have the time and inclination to sift through it much less be able to separate the wheat from the chaff.
I know they are not popular around here but what happens if we stick to the FACTS.
This site posts FACTS in many places in the way of #s. Members may lie in their OPs or stretch the truth in responses but those #s do not lie and merely confirm the "never ending wild popularity" of certain topics.
For anyone interested in learning much about what makes all us Humans tick, I highly recommend Helen Fisher.