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 is lean for data exchange between machines.
But in the LLM economy, the currency is tokens, not bytes.
To an LLM tokenizer, every bracket and quote is a distinct cost. In our tests, this 'syntax tax' accounts for up to 30% of the payload.
We chose a line-oriented format to minimize overhead and maximize the context window for actual commerce data.