Champion Sales (Read for Cats in space and signs of Alien life)

I know Riot puts champions on sale so that people will use "real" money (Riot Points) to purchase them. I'm wondering why they don't offer some sort of IP discount as well? Even if it just knocks that champion down a level in price say from a 6300 to a 4800 for the same duration as the RP sale is happening? You would still have the people that really want that champion purchase it and it would also give the people that like to spend there money on skins and earn champs through playing the game a break. Any thoughts or reasons on this? @Riot