Moving is harder because property taxes will suddenly reset to much higher values. Long-term owners are partly protected from tax increases.
We also have high transaction costs for homes. Considering both sides of the transaction, something like 10% of the home's value is eaten up by various fees.
So nobody can afford to move. BTW, this is a huge source of our traffic problems, the other being school districts.
So I think there is something to this. Moving around probably got much harder due to rising real estate prices.