Well, that's sure only half of the truth. About 90% of all mobos are used for pre-build systems form DELL, IBM, HP and all the others and will never be changed anyway. In fact there are a lot of facts, that force the change of sockets, like adding build-in graphics, build-in memory controllers with various number of channels. Even raising the front channel speed and power consumption needs a new socket. Did you know, that only half of the pins is used for data. The other half is power and ground. And that you need a ground lane/pin between two high frequency data lanes to keep them from interfering, because they are to close? You can find some white papers on the net about this problems.