Are JSON schemas necessary for defining the structure of a JSON?

Question

I am asking this because I see that the current JSON schema draft (http://json-schema.org/) proposes to have the schema of JSON in the following way:

for the JSON :

Answer 1

Until now have never been necessary and in the short term I don't think it gets to be.

I personally like JSON because its simplicity, portability and flexibility.

I don't see even major brands using that schema so until now they don't take its serious.