Party play should be disabled in ranked TFT. Players teaming up, communicating, playing different comps that don't compete for the same champions - a massive advantage to them and a massive FU to the random unlucky solo players who get filled in.
It works in more than one way: in Platinum games I often see 1-2 very low ranked players with the same club tag as some Platinum player. Or sometimes without a tag, but it's obvious what's going on. They can't possibly be matched against me if they are not in a party with their high ranked friend. They are feeding him and throwing the game, ensuring that even with the worst possible luck he can't finish lower than 6th and lose too much LP.
TFT is a solo game. The party mode should only be available in unranked games. It's just not fair.