These aftermarket harness company themselves usually have a pretty shaky understanding of basic electrical theory, then you get the consumers who dropped big money for them along with install wanting to justify their purchases preaching the gospel that it's the best money they ever spent. It's a weird niche in the market, I feel like any installer or DIY would be able to rig their own setup just as easily (and way cheaper and cleaner) vs purchasing a pre-made harness.
Most of the recommendations are massive, massive overkill for very low power draw devices.