"As this incident shows, it only takes a silly accident to change things dramatically. The party had left a route-card detailing their intended route, which is essential, and had done almost everything right."
Whilst some will jump all over the salient "almost everything right" section of that article, those of us slightly less up ourselves might feel a tad of empathy with the walkers involved. At one time in my distant past I climbed Ingleborough with the temperature at the bottom being around 24c and that at the top around -1c. Weather changes, but with more poignancy - sometimes it doesn't!
We're told by those in the know to prepare for all eventualities, yet at the same time 'don't over burden yourself with too much tackle'. A happy medium must be found, is there a Naismith's rule for calculating the point at which point this medium is reached? Good judgement will be the clarion call, but do any of us know all of the facts? It's easy to criticise...it's not always helpful retrospectively.
Perhaps it's worth pondering over this parody: if there were no people needing to be rescued, there would be no Mountain Rescue for the freak accidents that do occur.