[watwut]

Neither John Carmack nor Donald Knuth nor Bruce Schneier became famous because of blogging. The only one who became famous for blogging was Joel Spolsky who blogged more as technical manager or entrepreneur then engineer. Joel Spolsky also blogged when light management blogs were rare and would show up high in google search. It was something new back then, it is not something new now.

[michaelt]

Knuth and Schneier both wrote highly influential books, though, which I would argue are examples of programmer plus writing skills equals famous programmer

[watwut]

Which is not the same thing as having blog. It is completely different. They also wrote under different conditions as blogs are written - book was paid work and publishers pass your books through editors.

Also, Bruce Schneier is not a programmer. He can code, but the bulk of his work is not programming.