[magduf]

The problem with this idea of "duplication" is that, in reality, it's never been shown that monopolies are actually highly efficient. Humans just aren't very good at being efficient when they aren't forced to, and competition does that. The places where we do have monopolies that work out OK are where there's heavy government regulation, and even there the results are never as good as an industry where there's highly competitive private industry; it's just that, for some things, having a regulated monopoly is better than the alternative: we see this for utilities, subways, etc. where competition doesn't really make any sense or just isn't feasible (you can't really have 5 different subway lines going between the same 2 points in a dense city).

In reality, humans are frequently lazy, corrupt, incompetent, etc., and so in a market where there's healthy competition, the presence of competition provides a check against these problems, giving consumers an alternative when one player screws up too much. With a monopoly, there is no alternative, and no incentive to do better, unless it's being heavily controlled by the government which has to respond to voters.