Even on the web, imo a large portion of the interesting stuff done today is strongly based on decades-old expertise. For example, Google's V8 JS engine was buil

Even on the web, imo a large portion of the interesting stuff done today is strongly based on decades-old expertise. For example, Google's V8 JS engine was built largely on techniques developed in the late '80s and early '90s for implementing Self and Smalltalk, by people who had developed their expertise in the Smalltalk world. That expertise didn't remain static, of course. But it was highly relevant and formed the basis of the further developments, which is why Google specifically went out and hired those people to develop V8, because having expertise in implementing Smalltalk efficiently is useful if you want to implement Javascript efficiently. If you approach things very shallowly, learning how-to-set-up-technology-stack-X type bags of tricks, those become obsoleted quickly, but lots of technical expertise is quite durable.