The information is spread out because it evolved over a period of time, during which it expanded to include newer and simpler methods, newer tools, and to cover more firmware versions. Each new firmware update required additional instructions to overcome the new problems it brings with it.
The instructions attempt to be GENERAL, to be a guide to help you LEARN how to debrick your kindle. The "simple debricking" method involves flashing (mostly) unhacked firmware images instead of difficult case-specific repairs. These methods have even been extended to successfully debrick K3s (replacing MfgTool with Advanced Toolkit).
To have separate guides for EACH firmware version of EACH kindle model would lead to people using the wrong guide. We already have cases of people trying to flash K5 diag kernels on top of K4 main partitions. It would be worse with too many guides to choose from (especially if the user does not know what firmware version is on his bricked kindle).
Better to just flash the oldest known good firmware and upgrade later.
Besides, there are reports that people have had trouble with the 4.0.1 firmware images, so you really should start with 4.0.0 anyway.