Nonsense. Foreign trade was only about 7% of GDP. Smoot-Hawley had very little to do with the Great Depression.
So what if it were 7%? The housing market was a small percent of GDP, but it's collapse had ripple effects throughout the entire economy.
American exports fell from $5.5 billion in 1929 to $1.7 billion in 1932. American agriculture customarily had exported over 20 percent of its wheat, 55 percent of its cotton, 40 percent of its tobacco and lard, and many other products. When international trade and commerce were disrupted, American farming collapsed.
The Smoot-Hawley Tariff was a disaster.