You said factual. But what is factual for you and I may not be for someone else. There are a lot of recollections in the article where sama remembers one version or doesn't remember at all and the other party remembers something else. Combine that with the nature of the article and the legal issues considering egos and sums involved. To top all of that New Yorker is known for fact checking that is exhaustive to the point of paranoia.

I am just speculating but if @ronanfarrow is still checking the discussion here, it would be amazing to hear the actual reasons.

Very easy to explain: Legals.

Every good journalist knows that when you say potentially damaging stuff about very powerful people, you must be able to prove everything you say. So, you don't say "Sam Altman is a fraudster" because you (likely) can't prove it in court. Instead you say "Person A said that Sam Altman promised X and then reneged" and if anyone challenges that you show "here's proof that person A did tell me that".

If you want to be extra cautious, you only report where you have multiple witnesses agreeing on it.

> I don't get why writers do this.

Do what, edit?

It keeps it shorter.