Why the hell do people assume that there are only 2 social networking websites ? There are tons of social networking websites and ones popular in the US or euro

Why the hell do people assume that there are only 2 social networking websites ? There are tons of social networking websites and ones popular in the US or europe arent necessarily going to gain traction internationally. They may or they may not. There is just no way to know right now. In India for example Orkut is far more popular than Facebook.