There are two distinct things about this - the tragic event itself and then the lies and coverups afterwards. I'm talking about the day itself.
The actual event was a terrible accident. Decisions were made on the day that turned out to have tragic consequences, but were basically someone trying to do the right thing in the heat of the moment and getting it wrong.
To isolate an individual as being 'directly responsible' for all the deaths seems to be just satisfying some kind of mob instinct to have a bogeyman that we can metaphorically lynch for the crime.
As I recall from the news, the judge did a pretty good job of railroading Duckenfield into admitting he caused the whole thing, with a series of leading questions, something like....(I'm going from memory here)..
'You gave the order to open the gate'...'yes sir'
'If the gate been opened the fans wouldn't have got in'...'yes sir'
'If the fans hadn't got in there wouldn't have been a crush'...'yes sir'
'If there hadn't been a crush 96 people wouldn't have died'....'yes sir'
'Therefore you are directly responsible for the deaths of 96 people'..(thinks about this one for a while as it dawns on him he's been stitched up).........'yes sir'.
In actual fact there were many contributing factors, not least the fact that we used to cage fans behind bars like animals at the time. It would be just as valid to say the cages were directly responsible for the 96 deaths.