[tripletao]

Because even if a part is marketed as compatible with a well-known part, most buyers won't add a new, allegedly compatible part to the AVL (approved vendor list) without some level of engineering review. This guards against the kinds of incompatibilities that the article notes. Depending on the buyer, that review might be "yeah, [vendor] seems legit, fine", or a complete test build and evaluation; but by marketing their part as a counterfeit instead of a second source, the vendor bypasses that hurdle entirely.