||01-12-2013 03:11 PM
Not playing the meta isn't bannable, but I'll agree that certain things are like shooting your own team in the back...
From the Summoner's Code:
1) Support Your Team
“[Teamwork] is the fuel that allows common people to attain uncommon results.”-Andrew Carnegie
While we all carry a diverse set of individual ambitions and expectations into a game of League of Legends, once we hit the Field we’re a part of a team. For better or worse, our fates are intertwined with that of our teammates. Once the game gets into full swing, you have to make a choice between being a positive force for your team, or contributing to your own demise.
Being a good team player begins at champion select. Be open minded when considering the needs of your team. If you’re the last one to pick, try to fill a niche in your team that hasn’t already been filled. If everyone’s picked and something stands out as a deficiency in your team composition, try asking for another player to fill the gap, or change roles to embrace that responsibility yourself. Remember, that by taking on a role you don’t normally play, you’ll learn more about unfamiliar champions and increase your own skill level.
Once you get in game, try to keep an open line of communication. Warn your teammates if someone is missing from your lane, or if something is placing them in immediate danger. If they’re not paying attention to chat you can always try pinging the map. Just remember that one ping is enough! Also, remember that you have to be there to contribute, so don’t leave the game or go AFK! Encourage players who are having trouble, and congratulate those who are playing well. And most of all, if you’re having a bad game don’t take it out on your team!
Emphasis added. As others have said, a support who takes half of their AD carry's farm is putting the team at a disadvantage.
I saw a game recently where a Leblanc who called mid and another (who called top or mid) ended up both going top, when the team expected Leblanc mid. Turns out they were a duo queue who didn't feel like going meta. The jungler, I think, ended up going mid, enemy top got much more farm and got fed, mid lost lane, and the game was lost. A support sealing an ADC's farm when the enemy ADC is getting all the farm (and this duo queue) end up contributing to their own team's demise, but if they're polite, they didn't do anything reportable.
I've seen arguments for "assisting enemy team" by crippling your own team, but then it's left up to the Tribunal, and I can't say which way that would go.
So is it bannable? Not really. But does it hurt their team? IMHO most of the time, it does.