Department of exaggeration of importance of books, the real ones

From Timothy Egan of the New York Times, in an article on the new iPad that will kindlepete:

The last outpost of books in Laredo was a second-tier chain store selling the usual ghostwritten celebrity tell-alls, branded fiction and political screeds for people who need more empty calories in their one-sided cable news diet. But if Denver were to lose Tattered Cover, or Portland lose Powell's, or Washington, D.C., lose Politics and Prose, it would be like ripping one lung from a healthy body.

Probably not would be like.  Curious about the imagery ... why ripped from a healthy body?  If the body were unhealthy, ripping the lung not as bad?