: and why even a supreme
: intellect doesn't mean you aren't doomed to repeat history.

I personally believe that the Cortana we see in Halo 5 is not some kind of corrupted/evil version, but rather, as you said in the article, it's Cortana doing what she thinks is right. That said, Cortana immediately embracing the Mantle in Halo 5 was somewhat jarring. It would be nice to have learned more about what happened when she encountered the Domain, how her rampancy unraveled, and how she came to the realization/decision that it was time for the Created to take control.

"We are the Flood. There is no difference. Until all space and time are rolled up and life is crushed in the folds… no end to war, grief, or pain."
—Silentium

Not so different from reality, is it? Although we do still have joy, beauty, hope, etc. I guess that's "The Gravemind Difference". Extinguishing the positive vibes, man. How that ties into the possibility that the Precursors/Flood might still be testing humanity, I do not know. Despite being disturbing, I love this section in Silentium:

"It [Precursor/Flood dust] brought only disease and misery, but that was good, we saw the misery and found it good.
All that is created will suffer.
All will be born in suffering, endless grayness shall be their lot.
All creation will tailor to failure and pain ...
That is what we bring: a great crushing weight to press down youth and hope.
No more will.
No more freedom.
Nothing but agonizing death and never good shall come of it."
- Gravemind, Silentium

I just love it.

p.s. The Precursors, the Forerunners and the Created can all take the Mantle and shove it.