Hmmm never heard of that before.
That's ok, because it's not true. It's easy to tell if a customer purchased something directly from DISH, it's recorded on the account for the life of the account. The other issue regarding DHPP is probably closer to the truth.
That said, DISH does sell parts directly to customers (what type of parts are restricted to certain "must haves".) What you got was a "call your retailer" response, due to many retailers getting upset when the CSR doesn't send the customer back to them for service. A good retailer should always tell you to come back to them anyways, but that's neither here nor there.
All equipment has a "one year warranty" (yes, that little quote has a dozen different meanings depending on the situation.) That said, the warranty lies with the original seller, not anyone who purchases that equipment third party. I won't get into the finer points as to how and when that can be verified, but suffice it to say, those two points are why the CSR responded that way.