I saw those photos as well, and the presence of steel cables with turnbuckles to reinforce the structure lead me to believe that the damage was known and someon

I saw those photos as well, and the presence of steel cables with turnbuckles to reinforce the structure lead me to believe that the damage was known and someone decided that the minimal reinforcement was adequate. I suspect that if that was the primary cause of the collapse, the NTSB would have mentioned it directly already. Either way, we'll know eventually.