WHY AN AOC
The whole point of an AOC is that several people are accountable for the safe operation of the travelling public/customer.
That is why they exist. They are expensive to operate and entail much effort to obtain, but at least gives several layers of protection to the public who may not realise that this is needed.
In practice the buck stops with the pilot, but we all know there is always someone who will fly even if it means leaving their comfort zone.
Because this is a high profile case (like the Shoreham accident) I suspect the resultant investigations will reach into many levels of aviation and come back to affect even simple 'club' flying.