Have you ever tried to find anything underwater in a reasonably challenging environment? I mean even in a spot where the parameters would seem to have it down to a fairly limited area ("it must be around here somewhere...", kind of thing).
Having failed after an initial, frantic, emergency search the group brain kicks in and tells you "it's not here, let's spread out guys". The theories get wilder from there on out.
I've been there, and also (totally coincidentally) personally involved in the final discovery and subsequent recovery 6 months later, which was (somewhat predictably and very much like this case) very, very close to the LKP
Nothing like the AF447 depths though, my experience involved puddle depth, a mere 200 fsw. I consider it fairly amazing they found any further trace mid Atlantic.
I believe the pinger(s) must have been down. There is no other logical explanation for not picking up signals during the first searches, unless I'm missing something totally obvious, generic conspiracy theories notwithstanding.
Whatever, this and the TechLogs original thread have been tremendous, thanks y'all.