pubstomp new players because new players don't know to buy oracle's elixir. If invisible champs are never free, they will (believe me, a lot of people I've played with have NEVER bought an oracles, even with invis champs in the game) never buy an oracles.
See what I'm getting at? It's like you're not teaching a student multiplication but expect him to get a good grade on a test over it.
They will get raged at hard enough for dying to Eve/Twitch once they hit the mid teens. They will either learn then or stop playing. No need to force them to endure a mouthbreathing neckbeard who makes a smurf account and plays a stealth character for the lulz.