Huh. Guess I misremembered that. It’s been a while since I looked into it.
In any case, the point stands. The carts are identifiable but not tied to an account. They clearly keep some record of who (optionally) registered each cart for these purposes, but carts can still be used across multiple unrelated accounts and consoles simultaneously and Nintendo still has no way to differentiate a first purchaser using a cart across consoles/accounts versus someone having re-sold a cart.
They used a code-in-box for that on physical releases, IIRC. The carts are identifiable, but they´re not tied to an account, that I know of.
I recalled differently so I looked it up. Here’s a video of a random person claiming their points. No code-in-box, just the console phoning Nintendo with cartridge inserted.
Huh. Guess I misremembered that. It’s been a while since I looked into it.
In any case, the point stands. The carts are identifiable but not tied to an account. They clearly keep some record of who (optionally) registered each cart for these purposes, but carts can still be used across multiple unrelated accounts and consoles simultaneously and Nintendo still has no way to differentiate a first purchaser using a cart across consoles/accounts versus someone having re-sold a cart.