I think it might have to do with people considering 40 as very old in Silicon Valley and those in their late 20s and early 30s have barely learned this lesson.
I feel like other fields of engineering don't have such a dismissive approach to their own pasts. Show an electrical engineering class an old analog instrument and there's generally wonder and curiosity. Show a computer science class a slide with a 1 MB hard drive compared to an 1TB SD card and there's generally ridicule and laughter. "Look how stupid they've been", not "we've learned many valuable lessons since".
Anecdotally speaking, the average web developer does not have any formal computer science education. Most are self taught or attend a bootcamp or two at most. They have excellent vocational skills, but little knowledge of anything in computing outside of their narrow path of learning.
"Progress, far from consisting in change, depends on retentiveness. When change is absolute there remains no being to improve and no direction is set for possible improvement: and when experience is not retained, infancy is perpetual. Those who cannot remember the past are condemned to repeat it." - George Santayana (1863 - 1952) [The Life of Reason (1905-1906) Vol. I, Reason in Common Sense]
This neatly dovetails with the thoughts that were floating in my head. This part, is the explanation I believe, for the current state of programming, "when experience is not retained, infancy is perpetual."
This has wide reaching effects, one of the more obvious ones being that 20 year old knowledge seems ancient to most.
Sadly on several countries this is a thing, which also contributes to a low level of expectation, regarding the quality of delivered work.
My Informatics Engineering degree certainly did include historical perspective of previous languages, operating systems and hardware architectures.
