Why were freeweek champions allowed back into ranked?

Who thought it would be a good idea to allow access to play champions like Yasuo in ranked, without even having to own him?

I've already been in a few situations where someone assigned bot lane just casually picks Yas mid first time, then proceeds to absolutely flame and throw the game.

At least new champions can be banned to prevent 95% of the player base from feeding with him, but freeweek champions in ranked should be left in season 2.