Blood wants to emphasize that weblogs are easy. To emphasize this, she tries to deemphasize the details of specific programs and ends up arguing that software doesn't matter. That's not going to appeal to Winer, who makes weblog software, and who felt himself slighted in an earlier Blood essay. It also leaves Blood in an awkward place: if weblogs are easy, who needs a handbook?
The real difference between Blood and Winer is a deep-seated and widespread rift among computer writers. Blood thinks software is about selecting a product: you go to the store and choose based on price, performance, and color. Winer thinks software is about crafting an idea: you learn everything you can, you gather up your tools, and you try to build something better.