The AAIB does not lay blame
Overstress, there's probably some technical distinction, but simply stating facts can sound a lot like blame. For example here's a sentence from a random AAIB report:
The accident occurred as a result of the pilot continuing to land from a destabilised approach, rather than performing a go-around.
(Gulfstream 550, HZ-A6)
How does that differ from blame?