Biomedical information can be divided into broad based and niche based titles. Broad based titles are for the generalist reader and are used a lot. Because they are considered value for money, most libraries buy them. Niche based titles are, by comparison, only used a little. Professor McCabe studied how libraries decide which journals to buy.
Most libraries have to satisfy a variety of readers and so try to buy a portfolio of journals.
To achieve this they omit the more expensive, niche based titles. However, specialty libraries have no choice but to buy the titles relevant to their field - a library at a stroke research centre would be incomplete without a leading journal on atherosclerosis. Hence, Professor McCabe suggests that commercial publishers have a core of consumers with no choice but to pay the marked price. In effect, selling less for more makes more profit than selling more for less. If this is true, publishers are effectively restricting the dissemination of scientific information for commercial gain.