I think that all postdocs should stay in academia, why else would you do a postdoc? I assume (maybe wrong?) that most of the postdocs had intended to stay when starting the postdoc.
Postdoc can be very advantageous on a resume. Where I am, if it's remotely related, you start at a higher engineering level than a PhD.
You can do research during your postdoc with chill timelines and pretty much 100% autonomy on your topic and then bootstrap a company with the ideas you've developed during said postdoc? In many countries the postdoc owns the IP of the research they're doing