How do you think Honey gets the "discount codes"? The way these platforms become successful is becoming advertising arms for the shops themselves. They can then get exclusive codes in exchange for a cut, and tell the advertiser that they can target better customers due to their tracking.

All the incentives are bad

What if you bought an android phone, and could ask them for the source code to the Linux kernel on it, but if they caught you sharing it online, they would not allow your phone to update to the latest Android version?