Yummi Most Trolled champ?

Yummi is the most trolled champ in League. Attach and go afk in any game and you will get experience. why Riot can't fix the attach feature is beyond me. why not add a cooldown for the length of attach? you can attach for 60 seconds then must deattach for # seconds and then reattach. i have had so many trolls/bots pick yummi afk and lose me games. Does Yummi need to be fixed?