This is not used for tea sourcing. The document explicitly states its purpose as being for the preparation of tea for sensory tests. It has nothing to do with brewing tea for enjoyment.
Sensory testing (which is what is what I and my company specialize in) is a large component of tea sourcing and absolutely part of the process.
To illustrate this:
Just as coffee has "cupping", a method of preparation used for sourcing and evaluation but which no consumer would ever use to prepare coffee for enjoyment....
Commodity tea has this ISO standard (also called cupping).
The reason that this method, over a method that results in a better tasting cup is used, is because commodity tea is selected via flaw minimization and consistency testing.
I'm unsure why you presented the entire point of the conversation as if it was a gotcha, but assuming it was a genuine mistake I can only suggest that you read my comment again.
My point was that outside of the most commodity level tea sourcing, no one uses these "standards".