Thing is, you would only be able to get these certs if you are a PUR member, so what they are essentially doing is reducing the actual value of your PUR discount benefit. Shady shit
I agree that is not ideal and is not in our favor. But they're not lying to us about how it works.
If the way certs are applied is disturbing, then you should be complaining about PUR elite too because it reduces the purchase price by an additional 10%, which means elite doesn't earn 50% more points than pro. Instead they earn 33% more.

Crying about rewards systems that pay you 2% to 3% is rediculous.
Power up rewards points are the equivalent of skee ball tickets at the arcade. If you're trying to buy the big screen TV with skee ball tickets you're getting hosed. Don't get me wrong, a bonus is a bonus.
And it's not shady if we know about. I'd agree it's not ideal. You just have to know how and when to use points/certs.
Shady is when they sign you up for the X1X notification list w/o permissio. Or when employees just tack on disc protection without asking.