I think you're spot on with that comment. Someone who works in a field that has easily transferrable skills; e.g., computer programming, project management, etc., they can probably stay in one moderately-sized city or region and maintain a steady income and mortgage.
If you work in a field that's subject to layoffs and regular cutbacks, or have a specialty skill where movement between jobs might mean picking up and moving to a new city, it makes little sense to lock yourself into a decades-long mortgage.
You might have to sell underwater, or in a down real estate market. Not the best for coming out ahead financially.