Why on Earth would they go through Viglink, rather than modifying the URLs themselves? Is it that hard to add `&tag=reddit` to the end of an amazon.com url?
1) Maybe Viglink offered a deal to get exposure. I never heard of them until today.
2) They claim to cover 30k merchants.[1] Maybe there is a lot of money for reddit in the 29,999 other sellers too.
Potentially this also opens for other use cases such as substituting the product name with a link to buy, maybe useful in some specific subreddits.