So basically you’re saying one of the best things you can do for yourself as a dev is be young.
It’s a well-documented fact that as people get older their fluid intelligence declines.
If you predicate your tech culture on requiring high fluid intelligence, you (a) make less readable code since the people writing it have more working memory and can hold more lines in their mind at a time and (b) break long-term institutional memory resulting in the reoccurrence of solved problems.
At the level of organizational architecture, a culture of emphasizing fluid intelligence as the strategy for attacking problems and adaptation causes serious losses of efficiency, and hence fluidity at a higher scale.
Ensuring compatibility with greybeards’ brains is key to long term success, and that means respecting an upper boundary on the rate of tools change.