That solves bandwidth. It fails on tokens. JSON syntax is heavy. Brackets and quotes consume context window. More importantly, Schema.org is a dictionary of facts. It lacks behavior. It defines what a product is, but not how to sell it. It has no concept of @SEMANTIC_LOGIC or @BRAND_VOICE. We need a format that carries both data and instructions efficiently. JSON-LD is too verbose and too static for that.
> JSON syntax is heavy.
I'd say it's not heavy. JSON syntax is pretty lean compared to XML.