Only a partial answer to your question (there's plenty of good ones), but it reminds me of the time I reached out to the CTO of a small startup looking to hire a director of data science.

I've lead a few teams before and have a decade+ plus of experience at a range of companies so I had a pretty reasonable idea about what's out there, and I figured it was a small startup so I might be a good fit.

I got a pretty blunt response that they were looking for someone that had managed teams for over 5 years, preferably at a single org. Not unreasonable but when I looked at the CTO's linked in they had only ever managed their current startup and only for 3 years at the time of the discussion.

I just found it curious that they felt the job of CTO could be learned pretty much as you go, but anyone without their target experience wasn't even worth talking to.

It looks like they had major layoffs a year ago, and aren't making much of a dent in their space so it's quite possible that "survivorship bias" is a big part of it as well.