Stupidity or nefariousness? Probably both. I don't feel like I can fix either.
The truth is just that we don't have actual user manuals anymore. Either the things that went into the manual are now built into software, or they expect you to look it up on the internet. So the only things that remain are legal disclaimers and very basic instructions, like how to turn on the thing so that the software can tell you what to do next.
So they don't tell you how to tune your carburetor because you don't need to do that anymore, it is all injection and the ECU software does the tuning, but the lawyers insist that it should be mentioned to not drink the battery acid should an idiot decide to try it and sue the company.
1. Quick setup guides. 2. Warranty information. 3. Warnings of not trying to fix yourself.