I have started a 5Whys twitter brainstorming .
RT: for the Why question one level deeper towards the root cause.
RE: for one more answer to specific Why.
The idea of using the twitter as a medium was to leverage its RE/RT functionality as the way create a Q/A tree going deep in two dimensions Why1->Why2->Why3->… and WhyX->[A1,A2,A3,…] instead of single thread here.
Here I would collect results of this branstorming and suggest a place for long discussions.