Actually dealing with the ATF is quite different than dealing with many other government agencies. One clerical error can land you in serious trouble quick. An out right mistake can have severe consequences.
If you sell a gun here or there by the book it can be simple. Now if you start getting busy with volume the chance of something happening increases. That's when you want to make sure to be in good standing. If you have poor standing or even if they just don't favor you the rules can be interpreted or slooow service.
True horror stories are a chance for free education of the pitfalls. Your daily business can be stopped completely instantly without their help even if you have done nothing wrong.