there is a good reason why the committee chooses older researchers with seemingly outdated, decades-old contributions over younger researchers.
you can't award the nobel posthumously. in other words, once someone dies, they take their life's work with them to the grave without any further formal recognition. so older folks are prioritized because everyone knows that the younger folks still have long lives ahead of them, and their time to shine will come.
also, the reason why nobel laureates in economics tend to be older than the other sciences is because of the lag time of proving important contributions.
in the basic sciences, new discoveries can be overnight. of course, incremental progress takes decades as well, but the culmination --- the breaking point of a new discovery --- can be instantaneous.
in economics, which is better categorized as speculation of rational and irrational human decision-making, it may take decades to prove a theorem (especially in macro). there is no "overnight success". you can say the most absurd or correct claim such as "new neoclassical synthesis is the best monetary framework!" but even if it were true, it doesn't matter unless there is substantial evidence. and that usually takes decades because of long-term business cycles and novel, unprecedented crises.
the consequence of this lag time between when the seminal paper is published and when there is consensus in the field is massive.
example:
paul romer won the econ nobel in 2018. but the paper he wrote that earned him the nobel was actually his PhD thesis from all the way back in 1983, when he 29. he hypothesized that one of the most important contributions to long-term economic growth was ideas, and how it is free to distribute and re-use innovative ideas.
even if his hypothesis were true in 1983, it wouldn't matter unless there was substantial evidence of it. and you can be sure that the rapid growth many developing countries experienced post-1980s and onwards helped to support his claim.