Aren't you missing the point of the "swiss cheese" analogy? It merely describes that many accidents do not have a single cause, but are the result of a chain of events/causes. It doesn't say they're unavoidable, or indeed acceptable.
Those who use the Swiss cheese anology are saying, in effect, that if you slice the cheese thinly and keep twisting each slice - sooner or later a series of holes will line up which will allow human or mechanical error to cause an accident.
It merely describes that many accidents do not have a single cause, but are the result of a chain of events/causes
Here you are absolutely correct. Well, nearly! Most accidents have more than one causal effect.
Most of my job involves advising people in a - non aviation word now, alas - on how to investigate accidents/incidents/events.
As the threads in Rumours and News demonstate, there are 2 phases to the on line investigation here:
1. The 'What'. By this I mean the answer to the question, 'What went wrong?' The engineers love this one as do the armchair theorists. Most civil accidents involving carriers we have good accident investigators who will give us this answer with a darn sight more evidence than we will get here.
2. Then we get to the 'Who'. Here we arrive at that - oh so fun - finger pointing stage trying to pin the blame on someone. 'They didn't do their checklist'. 'Why didn't the pax alert the flight deck that the slats were not deployed'. 'Did they rush the repair to get the aircraft away?' You will see it all on Rumours and News.
But they tend to miss on the third:
3. We very rarely get to the 'Why'. By this I mean the root cause or causes of a systemic nature. Was it a training issue? Was it too much pressure being put on the crew to 'press on' by the management? Was it a 'culture' (I could do a lot more on 'safety culture' but this isn't the place) of the business? Were there flaws in the recruiting process (believe me, there almost inevitably are)?
I repeat - and will keep on repeating - my original statement:
All accidents are avoidable (barring 'acts of God' or the enemy); if you think they are not you are on the way to becoming a statstic'