Do we actually know that past bad experiences with the dive op has little to do with the current tragedy? I haven't been able to discern that one way or the other from the information and speculation provided so far. If someone can provide information to the contrary, please join the discussion.
I personally wouldn't discount a diver's past experience with the same dive op, unless it happened a long time ago. The way a dive op does business can be a valid component in a dive incident, and something that is routinely looked at in an official investigation.
Just my .02.
If its proven to be a repeat problem such as several people going out and finding that they dont do roll call then yes it could play a part in a current tragedy but for one person to say that he was let down by them not doing a roll call (This is only as an example so any similiarity is pure coincidence) would only be signs that a divemaster made a mistake on one occasion.
Now if the incident was the day before or the same day then yes it would be something to look at but from some of the above stated complaints it would lead a reasonable person to believe that the incidents they describe had quiet a significant time lapse between the time of their experience and the time of this experience. One person complaining to could be a sign of a number of things. If you recall the fish always gets bigger with each time a story is told as it holds a persons interest better.
Again unless its something relative to the incident in question or something that is concrete as a recurring problem it really does not help solve the delima of what happend to the diver nor what could have happend by bringing up the fact I or anyone else had a less then happy experience with a dive company on one or 2 occasions. This is only proof to me that a dive master or boat captain was being lazy or just not doing their job and many rotate their staff out which could mean that on this date in question they may have had a dive master and or boat captain who did do every thing right.