> raw algorithmic skill
It's been ages that I've been asked anything remotely algorithmic. My interviews are mostly about frameworks, how you fit in a team and whether you know / can be "agile".
Not even a Fizzbuzz, much less so quicksort or more special algorithms.
> and willingness to say “I don’t know”
That never got me anything in any interview/company. To be fair, I found a few smart and cool friends because of this, but they themselves don't look as if they've found a good job either.
Being hired (valued?) as a senior engineer is really hard.
I don't think the number of jobs requiring fairly deep systems or algorithmic knowledge has gone down, but the ratio has.