It is clear to me that this extension is a bait and switch or scam. When I first used it I was able to get an Amazon gift card from browsing. Nice, right? Unfortunately they stopped offering any kind of valuable cards for exchange. So at this point they're just taking your data and not giving you anything in return, which is just what the big companies are doing anyway (and that was kinda the whole point of this, wasn't it?). They claim that they are offering new worthwhile rewards, but these are perpetually "Sold out" (Note the quotation marks). I don't believe these are ever available, but in any event, it doesn't matter if they are – the average person will never get access to them, and instead is offered a plethora of off-brand, worthless discounts.
Surf