It’s based on lessons learned from creating and evolving production schemas at Shopify over almost 3 years. The tutorial has evolved and will continue to change in the future so nothing is set in stone.
We believe these design guidelines work in most cases. They may not all work for you. Even within the company we still question them and have exceptions since most rules can’t apply 100% of the time. So don’t just blindly copy and implement all of them. Pick and choose which ones make sense for you and your use cases.