Trying to think about the forces on the ends of the cables; when the wind is blowing and the big weight they support is bucking and the resonances of all these waves are interacting among all those cables... I kinda suspect there were instantaneous loads at times that were several multiples of the static weight. kinda expect that would count for more. Not that I know anything about it :)

It stood for as long as it did, and had more weight added than the original design called for: thats a pretty good win for the original design, i think.