My friend just recently started playing League, and I'm getting back into the game after about a 3 year hiatus. I've been using AI games to teach him basic skills, and practice champions that were added in the time I was gone.
Every AI game we play, there's at least one bot on our team. It's obviously a bot and not just a new player. They all buy boots as their first item, and throw out abilities at totally random times.
There was one game a few days ago where it was me playing Cho (one of my old mains), my friend trying Sona for the first time, and 3 bots. The bots did nothing but run down lanes and die to enemies. The enemy AI got fed to the point where I couldn't out-tank them, and they just instagibbed the poor Sona. It was the first time I can remember actually losing an AI game, and it felt worse than getting curbstomped in a PVP game.
My friend was really mad (understandably so), but I think I was able to convince him that this isn't as much of a problem at higher levels. That said, I can't even imagine what the experience is like for new players.