I completely agree with you. I actually love it when bots are on my team in vs ai. Funnest game I had was with 3 bots and a human draven that disconnected. If I didn't pick kogmaw that may have been impossible to win but since I was kogmaw it was fun as hell to struggle against a pack of 5 fed bots (it's crazy how they stick together when they get fed and just push down mid).
That being said, it's just flat out wrong. You should not be able to level up an account while not even playing the game. It's just cheating. It's breaking the ToS, so by definition, it's just cheating. Whether you think it should be allowed or not is another story. I wish they would actually investigate my reports because I don't report just for bad playing... I've grown to be able to tell when it's a bot I'm pretty sure. Now there's bots that even talk to deceive and avoid detection. But all they say is Push or WTF. Lol and they say it sometimes when nothing even happened.
So please riot, when I report for cheating and say I'm pretty sure this is a script/leveling bot, please take it seriously and actually look at it. If their match history is all 0/11 or 0/9 with hardly any cs, the only thing they say in chat log is push or wtf, and all their games are vs ai, look at one of their games and their patterns and you'll see its a bot. Ban that shit. ARAM bots might be trickier to detect. I had a game with a blitz bot that I'm really not 99% sure if it was a bot but I'm preeetty sure it was. It just acted a lot differently than a vs ai bot.
It's not like Riot benefits from these botted accounts. It hurts the community overall. If you don't care about your account that much, and they're easy to get to 30, trolling is gonna be a lot more prevelant. People have to feel like they have a lot to lose by trolling or being excessively toxic, otherwise why wouldn't you do it? (Other than good people who just don't get off on fucking with people)