That works okay at the "notify CDW and Best Buy" level (and to some degree, they probably do), but not at the "notify every non-chain store that is reselling computers" level. And then you're also placing the burden on every reseller to keep track of which PC models (and serials) they sell their customers indefinitely. Which, again, not a big deal at the CDW and Best Buy level, but much less practical for many others.