"I fail to see how that's better than a short 10 gauge wire, a short length of 8 gauge wire, a couple feet of 2 gauge wire, and a long 1 gauge wire to the battery."
The problem is not that this is dead wrong. It's not going to be a problem if all connections are good with good materials. It's that it's going to be a problem if something is not right in the many connections. Their recommendation is just trying to minimize the number of possible failure points, especially when done by someone who is not knowledgeable or diligent. Factory wiring has a lot of connections too. Virtually all aftermarket EFI mfr's use the direct to battery recommendation.