Reading through all of these threads today, I must say your comment makes the most sense. Tho not necessarily the Indian Ocean part.
My intuitive hit initially was something went wrong with the structure…which made no particular sense until I read your post here.
But what about the cell phones? How quickly would passengers go unconscious?
For an experiment, turn your cell phone off and drive about 20 miles. Then call your cellphone from another phone and listen to it ring. That is because of the way roaming works. And at that height, about twenty seconds if it was an explosive decompression. Most people were asleep anyway, and if the alarms for low pressure did not sound immediately because of a small leak, hypoxia would just creep up on them. The pilots have a separate oxygen system, but if this had been worked on and forgotten to be turned on, well...