Blogs are real cool, since they allow you instead of listening hundred hours worth of work read only most essential summary. But that makes them self contained thing, not a direct replacement. On the other hand, how many people really need and can follow gpu driver development in depth.
I think it mostly explained by that in earlier days most people who dived into programming did it because it interested them. Then it became one of most lucrative career path, and naturally it saw surge of people, who do not share same interests. Relative amount of people invested in dive bombing into meaty details dropped, but it quite possible that absolute amount have not declined by much.