This is indistinguishable from hoarder logic. Such things straight up don't matter on the scale of decades. The US DOJ has a policy of automatic declassification after 25 years.
I don't think you've been paying attention to the news.
Also the US government isn't a great example. JFK was assassinated in 1963 and all records surrounding that still haven't been released.
The idea that people don't care about secrets across the span of decades is utterly wrong.
And the US intelligence community is the greatest data hoarder on the planet, rivaled only perhaps by the combined forces of facebook/google.