There is a banking adage that if it's growing like a weed, it's a good chance that it's a weed.

A home is still the biggest asset that most Americans own.

It has become fashionable to rail against government intervention in the economy, and the FHA is a favorite example by those trying to show the government's overreach. In reality, the FHA shows how government action during the Great Recession forestalled a much worse economic fate.

Too-easy credit and millions of bad loans made during the U.S. housing bubble paved the way for the financial calamity and Great Recession that followed. Today, by contrast, credit is too tight. Mortgage loans are particularly hard to get, creating a problem for the housing market and the broader economy.

Global central banks are working hard to lift their economies through an aggressively easy monetary policy. The ECB [European Central Bank] and BOJ [Bank of Japan] are buying tens of billions of bonds and other financial securities each month in an effort to stimulate their economies, which is pushing down rates everywhere, including in the U.S.

It is hard to be enthusiastic about the economy's prospects when house prices are falling: Households spend less, small business owners can't use homes as collateral for loans and local governments are forced to cut jobs and programs as property-tax revenue disappears.

Buying a home wouldn't make much sense if house prices were likely to decline further; no one wants to catch a falling knife.