That's a very weird perspective. I bought my monitor, camera, lenses, etc all second hand, and obviously I've got warranty nontheless. Manufacturer Warranty is unaffected by resale, no matter the reseller. And if the seller is a commercial reseller, I get 12 months of Retailer Warranty on top, too. (I love in the EU).

The concept that warranty would suddenly be void due to "unauthorized" resellers or retailers is very weird.