https://www.nytimes.com/2020/12/18/world/middleeast/caliphat...
There's no excuse for this; the organization failed to justify its claim to be the "paper of record".
I'm not saying that's how it should be, but apparently that's how it was.
As an aside, I think you can see this happening in California right now. California (and more specifically SF) has been winning for so long that now public officials have drunk their own cool-aid and seem to think Cali/SF is some sort of magic place and it's all the things they've done which have made it tech mecca. Except probably it's not, and that will become obvious as everyone slowly wakes up to that.
This has lead them astray many times in much more significant matters. Once reported, they treat contrary evidence as innuendo in all but the most severe cases of contrary evidence. I think they only bothered with a significant retraction effort here because the evidence of their error was so compelling and public.
I think it was a case of the NYT quite openly deluding themselves.
The "ISIS as unconscionable bogeyman" story also helped sell the U.S. intervention in Syria, which was an ongoing objective on the NYT's part.