yes i wonder about that too. i never thought of myself as someone interested in economics, but i guess thats where you'd look for answers to why some markets are weighted towards winner take all and some aren't. my guess off the top is that it has to do with how easy it is to switch between two competing products, and how economies of scale work in the industry. if there is a big economy of scale, and its easy to switch between competitors, i think that makes for the biggest winner take all scenario.