It comes from Eric Drexler, the nanotech visionary. Pointer from Robin Hanson who I'm sure understands much more of what Drexler says than I do.
My guess is that at the margin, scientific communication would benefit from more blogging and less effort put into journal articles. We have a tenure mechanism that exalts the peer-reviewed journal article. This distorts resource allocation, leading to inefficiency in scientific communication and discovery.
Robin says he plans to cut back on blogging, which suggests that he does not agree with me about the relative marginal benefits.