Restaurant.com is not a good deal

I redeemed some air miles last night for restaurant.com to get some gift certificates. I'm disappointed that I did because it isn't a good deal at all. A normal user pays $10 for a $25 gift certificate. Sounds like a good deal until you read the fine print:

Purchase must be a minimum of $35-$50 depending on restaurant and also has an 18-17% gratuity included automatically. Also some didn't allow you to use them on a Wednesday or Friday.

I know this deal hinders on the restaurant but when I go to buy a gift certificate, I assume that the money I get is good towards my meal without restrictions.

It surprises me that there are sites out there like this that can still make a profit.