I'm 37 years in the industry. Four jobs. 1 year (starter marriage at a big company in a big city), 10 years (great startup with a great leader where the culture was destroyed after he sold the company), 17 (the best technical challenge for me, but small company bought by big company which outsourced slowly but relentlessly. I would have left five years earlier but in 2008 I was just happy to still have job. I did my best work there), 9 years (still there, now principal SE). I'm a serial monogamist. I think staying, being invested and caring is in my best interest and the company's best interest. The down side is knowing when it's time to go.
Similar to what OP said about short tenures, you need to find out why people stayed so long. Agreed it can lead to parochial thinking. I've also known long tenure seniors that are at best no better than juniors only a couple years out of school.
I hate interviewing candidates, but my former manager told me it was the most important thing I do. Choose my future teammates. An hour is precious little time to suss out competence and character.