What's the point? You'll create dimensions never used by users (CPU sensitive), you'll store files not used by users (storage), you'll miss some configurations

What's the point? You'll create dimensions never used by users (CPU sensitive), you'll store files not used by users (storage), you'll miss some configurations for sure. They're creating files once and store them in a cache (CDN and local cache). Basically, they are doing something similar to your suggestion minus creating unnecessary files.