I think the real killer is that they apparently dropped a nearly complete pre-production from Del Toro. They’d produced props, costumes, sets. They had finalized scripts, seems like all they were waiting on was a shooting date.
I saw an interview with Del Toro around when he was still working on At the Mountains of Madness, shot at his production company’s prop workshop. He was showing swords, costumes, and god damn molds and busts for orc make-up never used for The Hobbit.
All of it went in the bin and Jackson had just months to start from scratch.