Small businesses are thought to be rather inefficient because of fix and because of other issues that hamper the exploitation of increasing returns to scale in their size range. Yet, policies keep popping up that try to protect them. Why? Is it nostalgia, throwing us back to times were "better?" Or do we want to protect (inefficient) employment? Even this may be moot according to a previous post.
Ben Craig, William Jackson, and James Thomson claim that small businesses should be encourage because they have an inherent disadvantage on credit markets: there are information problems, more acute in downturns, that make access to credit more difficult for small businesses. Thus, it is good for a government agency to provide loan guarantees. Still, this does not address why we would want to have small businesses in the first place. If inefficient firms are getting rationed on credit markets, I am fine with that.