Is this re-inventing, or "classic" taxonomy/ontology tools don't apply?
An Introduction to Structured Data at Etsy
An Introduction to Structured Data at Etsy - Code as Craft
"Etsy’s taxonomy contains over 6,000 categories, 400 attributes, 3,500 values and 90 scales. All these hierarchies combine together to form over 3,500 filters. JSON files are used to represent the taxonomy."