You can report people for griefing, and refusing to communicate with the team. It's much harder to prove than toxicity, but it can (and does) result in punishment. Just look at the recent situation with the support smite singed. He was almost permabanned because he received a significant number of reports based on his gameplay strategy and how he communicated/interacted with his team. He wasn't toxic, never flamed, didn't troll or afk.
But his actions led to similar situations like yours, where he was out of lane often. In his case it was smite, and not teleport, but the result was the same. It leaves the ADC alone in lane, sometimes unable to farm safely. I don't know what rank your Taric was, perhaps he doesn't understand the concept of freezing a lane, or keeping it behind the river to avoid over-extending. Maybe he doesn't know when he should be applying pressure across the map when its a 4-1 split scenario. Unfortunately, if they are low enough in skill that they don't know what those things mean, then it's unlikely that you can explain it to them in the limited time of a game.
But I digress. The point was that you can report someone for things like that. One single report for griefing because they took minions and teleported away and didn't actually support in lane isn't going to warrant a punishment. But if they consistently ruin games in this fashion, and are reported for it, then they might end up being punished for it. Will it be a ban? Depends entirely on what tier of punishment they are on. Does it warrant a permaban? Probably not. The player might just be very unskilled at support, and people don't get banned for being bad. But Riot doesn't want to see people consistently ruining other people's games. That's the bottom line here. Just because it's harder to prove someone is griefing or trolling doesn't mean that Riot doesn't care when people do it. It just means that people have to be more detailed when they file reports for it, so that Riot has something to use when the system reviews the incidents.
