While there's no real obligation to use affiliate links, it gives coupon-posters incentive to keep the coupons flowing, and it's a nice way of showing your appreciation for someone who just helped you save $5/$10.
A bit of a break from the $10 coupons; I just posted a $5 coupon code on the Play-Asia coupon blog: LU-GBA-PYN
Don't worry though. I have more $10 coupons on the way. Enjoy!