Castiel said:
Stop getting so emotional and rude and understand what I'm saying. All sides are at fault. There is no need to be one of these zealots who attack anyone not on board with the crusade. Believing that the police were completely at fault and the fans contributed nothing to this catastrophe is just wilful ignorance.
When you're in a hole, it's good advice to stop digging. What I quoted of your post left little room for misunderstanding in my view. Hence my reaction.
I do agree with you that, as is typical in many disasters, there was a combination of events with some playing a greater part than others. But all the fans contributed to it was their presence on the day. I don't dispute that some didn't have tickets, some were drunk and some behaved like arseholes. But that's what fans did in those days (and still do) but it has absolutely no bearing on the reasons that 96 people died that day. To try to link the two, even if implicitly as you seemed to be doing, just perpetuates the lies of The Sun.
To answer the point about the safety certificate, my understanding was it was effectively an ongoing one but hadn't been updated to take into account changes made to the ground since 1981. So for that reason it wasn't valid and SWFC have to shoulder some blame. The FA didn't bother to check the safety certificate and there are questions as to whether Hillsborough was even a suitable venue.
But the overwhelming catalyst for the deaths was the failure of Duckenfield to use the largely effective operational management plan used by his predecessor. That would have almost certainly prevented a build up outside the turnstiles. The second critical failure was not monitoring or controlling the build-up of the crowd in the central pens, particularly when Gate C was opened. Then, once events had taken their course, Duckenfield told a blatant lie to Graham Kelly, which set off the cover-up. He also failed to manage the response of the emergency services, meaning some lives which were lost might have been saved.