What if it's a backend service that is not exposed to a frontend that receives html or Json. E.g a task that takes an id and a operation name and needs to fetch from the database a bunch of data to process.
You will add readyset between your backend and database in order to cache the data you fetch from db.
I'm answering the comment above mine that is asking for a user case. I'm saying that my use case is an example where json/html caching is not sufficient. 100% agree with you.