Hmm-there have been many great product managers with technical backgrounds and experience. (I was one). I think Michael is on to something in his post about how it is an effective way to help engineers relate. That said it isn’t a steadfast requirement and many incredible PMs are non-technical and many poor ones are. I don’t think this changes the job description I laid out for product managers at all.
One shift that is important is I feel like 15–20 years ago when I started my career, product management dictated to engineering what to build. Today I like seeing it is all much more collaborative. So having PMs engineers can relate to and collaborate with is important — technical or not.