I've seen various reports that the reverse is true, people are moving away from their family less than in the past, although I'm struggling to find the right search terms ("migration" is flooded with immigration results; "mobility" is turning up economic stuff...). Compare today with a century ago: how many places went from "barely on the map" to "huge metropolis" in the USA since then? How many look poised to do the same over the next century?

And I think when they are moving, they're similarly not moving to as "new" or "small" destinations - e.g. tons of sunbelt towns saw very rapid growth from young adults moving there in the 60s-90s. But many of those towns are still the ones seeing a lot of growth; anecdotally, my parents moved to Dallas after college. Where's the "new Dallas"? The cheaper towns with jobs that are being promoted are still the same ones as fifty years ago, and they're not nearly as cheap as they were then anymore. Combine that with rising population from immigration + the kids who grew up there and didn't move away, and you see a lot of cost inflation.