Hum, interesting, but SDMs still need to know how to code, it's even part of the interview process, do you know if this is true 100% of the time?
Don't get me wrong. My managers were (are) extremely smart. They did know how to "code" for the most likely definition of the word code. But that doesn't mean I would trust them to write a feature or to review what I wrote. They just didn't have the day-to-day knowledge to know what did and didn't work in the code base I was in.
And do I know if what is true 100% of the time? Asking coding questions in a SDM loop? I have no idea. While I was there, I was only on TPM and SDE loops.
In my experience, similar time there, three managers, none of them knew how to code, and their managers varied- one was decent, one was a DMV reject.
But when I say they couldn't code, I mean that literally-- for one example degree in criminal justice, no knowledge of software practices, etc. This isn't another way of saying they were "bad programmers". No bad programmers can make great managers.
This is not strictly true. I was at Amazon for 4 years (2004 - 2008 in Supply Chain and Retail), I had 3 managers. Only 1 of them was a former SDE.