Did border restrictions kill the US economy?

A very long and involved Sumner article. But the most interesting part is just one paragraph interests me:

"Imagine I’m debating Tyler Cowen on the question of whether the 2006 wealth was real in 2006. What’s at stake? I might argue that the wealth was 100% real, but later policies like immigration crackdown and tight money reduced the wealth later on."

So the idea here is that maybe there really was no housing bubble, but there would have been enough demand for the houses being built if more people were being let into the country. Very interesting.