A toxic combination of high authority gradient, low skill/knowledge levels and a complete inability to modify the plan when it was obviously failing had a large part in their demise. I wouldn’t heap the majority of the blame on the P2 as, yes, he wasn’t doing a very good job but there was no effective monitoring from the P1. The P2 also tried to intervene but without success, due to inadequate advocacy and the aforementioned authority gradient. If the P1 had become incapacitated, would the P2 have continued the approach? Probably not; would the P1 have done the same had the P2 passed out - much more likely as he had a track record of doing exactly that.
The airplane was far, far, within its limits
I can’t access the report from the country I’m currently in, but I’m reasonably sure they went a long way into the red with flaps/slats somewhere on the approach? Given aerodynamic forces increase with speed squared, it doesn’t take much of an excursion to get to ultimate design loads. They may have been where no test pilot had gone before, as TPs understand the much tighter margins when it comes to speed limitations...