I think Intel wants to/
has to sell cards in PRC at lower prices and so allows the AM chips to be put into cards manufactured for that market.
It means we pay higher prices for the NIC in the US. It can sometimes mean we get better quality and testing and warranty. There's the issue of trust too.
One might find a non-Intel, non-OEM card made for another market to work just fine or the quality might be lower.
The difference in branding/price/quality assurance warranty and price give manufactuers and sellers incentive to mislabel and misrepresent the product.
I don't like that we have to pay more but I do like the warranty from Intel. I don't like the mis-representation and don't want to buy the conterfeit stuff. I might buy stuff manufactured for that market if it had a warranty and was not mis-represented. Trust - trust whomever you choose it's more about risk managment.
Aware of this dynamic, I've taken care to get genuine cards from Newegg and Ebay.
The first (T2) I got from Newegg full price and it had a Yottamark sticker. It stopped working after a couple months and I got an RMA replacement from them. I verified the Yottamark sticker with Intel during the RMA process.
The second (T4) I got off Ebay used and I took care to look for the embossed Delta and it has a Yottamark sticker as well. It's working fine now and the T2 which is still going strong needs to go on Ebay.