Not only this, but this seems like it might be against the Groupon terms of service to deny the coupon outright.
According to the fine print on one of the Groupons I have, after the expiration date the coupon is still good as a voucher worth what the customer originally paid.
You're not entitled to the advertised deal, but that coupon is worth money toward goods and services. For example, your $25 coupon is no longer good for a $75 spa treatment, but you still have $25 credit at the spa.
It's not clear from the post that she didn't take it as a $6 credit. It seems that way, but the author never says that and it's not the point she's trying to get across.
According to the fine print on one of the Groupons I have, after the expiration date the coupon is still good as a voucher worth what the customer originally paid.
You're not entitled to the advertised deal, but that coupon is worth money toward goods and services. For example, your $25 coupon is no longer good for a $75 spa treatment, but you still have $25 credit at the spa.