IP lawyer here. Rayiner is correct, but he left out one piece of the explanation of why it's thought to be important to keep out free riders: The rationale is

IP lawyer here. Rayiner is correct, but he left out one piece of the explanation of why it's thought to be important to keep out free riders: The rationale is that, when innovators make significant investments in R&D, those innovators need a period of time in which to be the only ones able to sell the benefits of the innovation. Otherwise, free-riding copiers, unburdened by the innovators' R&D costs, would compete on price, which would drive prices down to competitive (i.e., marginal) levels that would not allow the innovators to recoup those R&D costs. And here's the important part: Such rapid price reductions, it's said, would discourage future investment in R&D, because innovators and their investors would think "why bother; I'm not going to donate my time and/or my capital for no return, just for the sake of being a benefactor to humankind." A simple analogy: Why bother spending the time and money to plant and raise a crop if your neighbors can come in and harvest the crop without paying you — among other problems, you'll be far less inclined to pay for the seeds and fertilizer it would take for you to raise the next crop. So goes the theory; the extent to which that theory adequately models reality is something on which I'm not competent to opine.