If you the assumptions you start with are wrong, everything you base them on is going to be wrong.
A 1 in 3 failure rate is huge ... but
the Phantom 3 DOES NOT have a 1 in 3 failure rate.
The "poll" you quote has zero validity.
You brought this up earlier in the thread and it this false assumption that makes everything else you write wrong.
It has been explained in many posts, particularly the excellent post #132 by Crispy.
I suggest that you read it ..
Campaign for the replacement of all P3A /Ps with old motors and shells | Page 7 | DJI Phantom Forum
But since the percentage of P3 with this problem is so much smaller than you have assumed and the majority are not showing this problem, it is much more likely that calculations were fine but some slipped through with a bad batch of plastic and/or poor moulding technique left some shells with thin/weak spots.
DJI have offered a shell replacement for anyone that has the problem.
That's as close to an acknowledgement as you'll get
I have no secret knowledge from DJI - only what I can gather from all the information that is available to everyone else.
On the evidence presented, I suspect that I know quite a bit more than you.
Starting with a few basics like reading and arithmetic.