Thanks for the note! I get what you're implying which is that maybe it's not the engineers who are biased to stay where they are, but instead it could be the recruiting mechanisms that are biased towards homogeny. This is an interesting takeaway. I do think Startups have the mandate here to do a better job positioning their companies, and finding ways to entice big tech engineers from their companies. I do think startups offer engineers a variation if nothing else, and often allow them to get closer to the business, and thus work on more critical problems.
Author here! Happy to discuss any of the specifics of the report, including why DataGrip is the best SQL editor on the planet. But seriously, here for any questions.