One example doesn’t strike me as a glib dismissal, particularly since this study was done in the United States.

They don't give an example, they express their impression rather than providing contrary data.

Do you expect an entire research paper in a single HN comment?

I don't really care either way. I was arguing with your characterization of their comment, not demanding that they retract it.

No, but I would expect HN participants to not dismiss a researched paper with a glib "feeling" that's utterly unfounded.

they didn't give an example but simply made an assertion, one that by the way is likely wrong, given that the East of England is generally upheld as an example of good mobility(https://www.theguardian.com/higher-education-network/2018/fe...), compared to the rest of the country.

Ah, I see. Then I shall counter: London has pretty good upward mobility.