User blog comment:TheTobarMethod/Do AP's Need A QSS Upgrade?/@comment-4921386-20130903232439/@comment-5545048-20130906194656

There is not a single champion in this game without an offensive ability. Therefore, buying CDR for whatever reason or whatever spell you need it for will always have the side effect of increasing your DPS done through abilities. Of course for some champions this is neglectable, but we're talking APC's here. Their damage is dealt through their abilities. Even when the CDR is only used to decrease the intervals of their spell rotation, that spell rotation includes damage. It's not that CDR can be used offensive, it will always be used offensive, be it intentional or unintentional, unless you would intentionally wait for your spells base cooldown.

Also, you didn't answer to my second point. Why would APC's need to upgrade their QSS