It’s not necessarily because owning a home is cheaper than renting a similar home and thus a buyer has more spare income to save. Right now, that is true for most buyers in most markets, because the housing crash pushed prices down much more than it did rents. But the rent-vs.-buy calculation varies with market conditions and personal circumstances. It didn’t favor buying in most places in 2006; it may not favor buying now if you don’t qualify for a low mortgage rate or aren’t sure when you’ll move next. Low purchase prices can be a great reason to buy a specific home at a specific time, but they’re not a justification for broad pro-homeownership policies or norms. And sometimes, a lower cost for buying is a product of those policies, rather than a justification for them.

But regardless of the investment characteristics of a home itself, a mortgage fosters saving. You make one monthly payment that is part consumption (interest) and part investment (paying off your loan balance) and so you save over time without specifically trying.

This isn’t an iron law; during the housing craze, banks offered “pick-a-pay” mortgages that allowed homeowners to decide not to pay principal in a particular month. Renters can conscientiously set aside cash every month on top of their rent payments. In general, however, a traditional mortgage locks you into saving every month unless you refinance or sell, and that provides a powerful nudge toward saving that renters don’t receive.

But a home mortgage doesn’t have to be the only place people get the saving nudge. Right now, the Obama administration is working with employers on a program called myRA, which would give more workers access to retirement accounts through payroll deductions at work. As an inducement to save, myRA participants will get access to an investment modeled on the “G Fund” from the Thrift Savings Plan for federal employees, which pays an above-market return on a safe, bond-like investment.