Because you can’t read the article by reading it’s number, and there isn’t enough room for the whole article on normally visible parts of the body (not to mention the cost of that tattoo).
The QR code would give you a way to copy/paste the id so you can actually give and, you know, read the thing.
A QR code can also just contain plain text. It’s just usually used for URLs.
Plain text can also encode plain text. Why are we complicating this?
Because you can’t read the article by reading it’s number, and there isn’t enough room for the whole article on normally visible parts of the body (not to mention the cost of that tattoo).
The QR code would give you a way to copy/paste the id so you can actually give and, you know, read the thing.