I think the blame comes from the fact Ford weakened the area by using three bolts compared to previous models that came with four bolts. I'm fairly certain there has not been any broken bolts on models that have four bolts, regardless of the abuse they receive, although I could be wrong.
Imagine buying a hiking shoe and that shoe handles all the abuse you throw at it as you hike the mountain hills, and then imagine buying the same shoe next year and the sole is thinner and the shoe laces are not as strong, and hiking those same hills results in the shoe falling apart. I would say the blame would be on the shoe manufacturer, not the hiker.
Edit: Let's not forget that Ford labels the Explorer ST as a performance vehicle, well knowing it will be abused.
The blame rests entirely on those people who use FORD's products beyond the manufacturers intentions.
To propose the notion that FORD is responsible for damage that occurs outside of their intended function belies common sense and reason.
The "hiking shoe" analogy lacks support on multiple counts:
The shoe was made for hiking, the ST was not made to be substantially modified and then live it's life at the drag strip.
The shoe was made to sustain specific wear, deviating from such is abuse, which parallels people tuning/drag racing/installing launch control chips in their ST's.
The shoe was made to operate within specific environments, any alterations to that and the wearer loses the right to durability claims, same as modding the ST.
I could go on ...
Lastly, let's not forget that FORD labeling the Explorer ST as a performance vehicle doesn't mean people can strap a Saturn V rocket to it and not call it abuse.
An exaggerated example? Well, then what arbitrary limits to do we put on the vehicle? 552 hp? 673 hp? Drag racing once a week? Once a month? Six times a day?
Performance Vehicles Do Not = Race Vehicles