"Your pain is the breaking of the shell that exposes your understanding."
-Kahlil Gibran, The Prophet
The spirit of that quote, for me, is in finding my own "understanding", not that of another. Easier said than done because it can be heart wrenching trying to discern the 'truth' from someone who is incapable of living truthfully. Why they said this or that... I don't know. I can accept, however, that the big picture overshadowing the chaotic details is I wasn't afforded honesty and 'truth'... and there lies greater strength/integrity/character on the other side of having lived with half-truths, lies by omission, and outright deceit.
The Big Book of AA states there are those who are, "... constitutionally incapable of being honest." With honesty being a hallmark of recovery and IMHO, there is no active addict who is constitutionally capable of being honest... and that is my best understanding toward an answer of "Why"?
Many Blessings,
Shaman