There's a difference between Bad and Clueless
And the boards never talk about it because we're all so quick to tell other people they're bad. "I climbed out of Bronze - and if you can't, you're bad." Agreed. Now that we've established you're a better human being than me, lets have a real discussion about players who show up in Ranked without any idea whats going on.
First of all, before we get into what to do about it, I'd like to think we can all agree that it's on par with trolling, even if that isn't your intent. As short as these games are getting, there are times when some of us have 1/2 games per night because of work, class, and whatever else. Showing up in your 6th game of the night on a new champ with no concept of the matchups you're involved with is asinine.
I'm all for carrying bad players. But bad players aren't the problem. For me, I can't stand the people who show up in ranked with no knowledge of champions, match-ups, items, or what to do after an ace (In bronze, the answer is always recall - which kills me). To this end I really feel like MMR alone shouldn't determine the match-up, I'd really love to see total games played in there as well. There needs to be something, because none of these people take feedback, they always think they're the best player, and for the love of christ they can never say "I'm not doing well, but that Mid is destroying his laner...I think I'll just NOT feed as my contribution." Every meet up is a Leroy Jenkin's attempt at heroism.
This was just a rant. i've given up on Riot doing anything about the legions of assholes that operate at the bottom levels.