I can understand what is annoying. I remember going into a farm party for T9 months ago, the group was really nice except 2 guys. I never solohealed the fight before that night and the other healer kept dying until the moment I chose to leave him dead, and one of the 2 monks almost wiped the whole party more than once ; and even though they were newbies (achievement at the end of the fight) they didn't say a word even if the PF was stating "Farming - experienced only". MNK got the weapon after our messy clear. He left right away with a "thanks" that felt like a middle finger :/
It happened more times than I can count, with every single turn I farmed, with EX fights (Titan & Ramuh were the worst) but since you can never tell who is new to the fight when you enter it, you can't kick until everyone dies and leave the fight, or when you clear and carry them.
The problem here isn't about farming groups being useless, it's just about avoiding conflicts and dishonnesty.