I don't THINK that every leather item is uniquely stamped. I could be wrong. If it is, I don't know that a one-of-a-kind SKU, or whatever, can be linked to the buyer. At least, the receipts given to customers do not list singular identification numbers for everything. Color, leather, size, yes, but not "75 cm rouge H togo belt number 84X1250B; 56/700," or whatever. Hermes still keeps information on bespoke saddles as handwritten entries in leather-bound books! Not, perhaps, the most techie of companies.
I just don't see how every single item could be tracked to its new owner, or how every one of those thousands upon thousands of people the world over could be contacted. I suppose everyone who bought a Togo or Epsom bag in certain years could be contacted, but as not all items are affected this would result in an enormous number of "false positives," if you will. But by all means, continue to be angry with Hermes' response to the issue. They certainly have not handled it perfectly.
And this is almost certainly veering off-topic, anyhow.