This thread demonstrates perfectly the rather uneasy relationship between Americans and the notions of efficiency, competition, and monopoly. When asked their opinion on any one of these issues, most people can give a fairly straightforward answer. The problem arises because there are, in many cases, contradictions (or, at the very least, tensions) between these areas that can make it difficult for them to coexist.
For example, if competition (which most people agree is a good thing) leads to greater efficiency among some firms (which people generally also see as a good thing), the result is often that the least efficient firm/s are forced out of the market (again, many people have no complaint about this). However, if competition acts continually to force the least efficient firm/s out of play, the end result is often an oligopoly or a monopoly (which most people seem to think is a bad thing).
Of course, this doesn’t always happen, but it is a rather strong tendency in a competition-driven market. The problem for many people, then, is how to ensure competition and increased efficiency without resulting in monopoly. Some call for greater government oversight to maintain competition; others believe that if the free market results in an oligopoly or monopoly, then that is fine.
The problem sometimes reduces to moral arguments over whether big or small businesses are “better” in some (not necessarily economic) way. This was one of the key arguments during the Depression, when some, like Louis Brandeis, argued for the role of small business in America and believed that, even if large, centralized businesses were more efficient they should not me encouraged at the expense of small concerns. This sort of attitude has roots in Jeffersonain ideas of a small-producer society.
If anyone wants to read a really interesting book on how these debates played out during the Depression, may i suggest the classic study by Ellis Hawley, appropriately titled The New Deal and the Problem of Monopoly: A Study in Economic Ambivalence.
As Rupert Murdoch once said: “Monopoly is a terrible thing until you have one.”