Information based product, esp. with strong social context, is highly related with its user group. Even if every product in the narrowed domain is exactly the same. They evolve to different products later and may not a better fit for other user groups. And yes, the policy barrier set by the state is also a major reason to provide room to have some follower strategy products survive and grow strong. But market value is not a key indicator here. Money can not buy you anything, esp. in information industry, in which a lot of people know what a substitute product can do.
Also, if you want to worry about Tencent, just try their products to see how polished they really are yourself.
In case you are interested, Porter five forces analysis http://en.wikipedia.org/wiki/Porter_five_forces_analysis is a good framework and start to learn to have some idea of how to exam a market in a more logic way.