Transparency.
I have links to items on this site that are part of the Amazon Associates program whereby I receive a commission on purchases made via the link. Amazon does not always have the best price on everything. If the very best price on the item is your main goal it would be in your best interest to comparison shop. If you want to easily purchase the item I have referenced on the other hand, the link will get you there quickly and I will know the content I am creating has some value to somebody.