[ivalm]

First, I accept that there are cases where extreme specialization is important. I just think these cases are few and far between.

The main skill for senior/staff swe is not in knowing or not knowing some technology, but rather

1. Picking things up quickly

2. Understanding/recognizing generalizable patterns and best practices in any tech.

Almost no job requires some extreme expert level knowledge of language/framework minutiae (obviously you do need some experience in particular tech). Almost every non-greenfield job has a ton of custom tech that has to be learned. Almost every green-field job needs someone with immense breadth.

Having been exposed to very many things people get to naturally see recurring patterns/best practices. When they see a new tech they are able to understand why choices were made. When new tech needs to be made they can draw from broad experience in what others did best. I really think this is most of the eng value of staff swe.