Why is Black Widow In Her 80s?
This write-up makes some good points, and is worth reading especially if you don’t know the history of Natasha’s history. I think it undersells two things:
The concept of “Russian spies” is indelibly tied to the Cold War. You can look at the MCU for a clear example of this: even though Natasha in that world is only the age of Scarlett Johansson, she still namedrops the KGB, not the GRU.
The Name of the Rose, the comic that, imo, made the best storytelling argument for having Natasha be secretly 80, is the version a lot of newer fans imprinted on.