If you talk to intel and former intel employees I'd argue the real rot is the dog-eat-dog internal company culture. I've heard from multiple people who describe an environment where you need to work for the biggest A-hole boss, since otherwise your group will get no resources, get canned, or otherwise perish. The teams compete instead of cooperate, and in a ruthless underhanded way.
The result is that projects get essentially sabotaged from within, as this is often more effective a strategy to survive than out engineering a competing team.
The fab has traditionally been focused on CPU's to the exclusion of all else. Completing a tape-out without deep internal knowledge and connections is essentially impossible. In one case OSU's engineering department was given a free tapeout run, which normally is a godsend to cash strapped universities. It was impossible to get a clean DRC taking months of fruitless effort by the beleaguered grad students, and a favor was called in from a friend who worked in layout there. It shipped with literally thousands of violations, but he was versed in what was real and what could be ignored. Compared to tapeouts at GF and TSMC this was all shocking.
So you have a company that has had diseased culture with broken tools/fabrication that previously masked these issues with monopoly level income flows now facing declining sales, real competition, shifting customer focus, and no real stomach to fixed a deeply entrenched toxic culture. What could go wrong?