From Tyler Cowen:
Between 1993 and 1999, the social network of the TRPG players had become seriously frayed. Even if you just looked at the network of Dungeons & Dragons players you could see this effect: People self-segmented into groups playing Basic D&D, 1st Edition, 2nd Edition, and within 2nd Edition into various Campaign Settings that had become their own game variants. The effect on the market was that it became increasingly hard to make and sell something that had enough players in common that it would earn back its costs of development and production. We looked around the industry and saw the same problem at virtually every company that had become successful.