[Discussion] What do you do with "it's only 3s" teammates?

I'm sure this has happened to everyone, probably less for those of you in Diamond and Challenger, but I am so offended when people Join a RANKED game in TT and play a character for the first time. I've learned pretty quickly not to flame my teammates, it really doesn't help. But I do normally ask something along the lines of: "why would you play a champ first time in ranked?" And I almost ALWAYS get: "It's just TT, who cares?". I cares! TT is all I play you jerks. Should I just go to SR games and play new champs in ranked? I feel like...no? Maybe.

Does this sort of thing actually stop at higher ranks? Will I ever be able to air for a game where all 6 people playing know the map and meta? sidenote what do you do about a yi?

Edit thanks for the advice. Also, references to how Summoners Rift is will fall on deaf ears; I've played maybe 3 games of 5s in the past year if that. TT4Life