You could argue an analogy to infection can be useful: it is not only, or not so much the number of viruses / books produced, but also the contagion probability

You could argue an analogy to infection can be useful: it is not only, or not so much the number of viruses / books produced, but also the contagion probability. Factors that harm infection, such as distance to the target (which, with more offer and tastes, increases); or competing hobbies (which harm time for reading and writing / virus life); or competing conversation topics (habitat competitors,vaccines, eliminated contagion vectors through hygiene)... They all can harm literature even with more viruses.