It kind of looks like people have forgotten what PvP is. Everyone wants to win, no one wants to lose. The pre-mades are just maximising their chances of winning, anyone can do the same, they're not being disruptive, they're not being mean-spirited, they're just trying to win. Nothing they're doing is illegal, their only obligation is to win for their team, there is no obligation to make sure the opponent teams have a good and fun match.

As for FL being as balanced as possible, if you want to get rid of the overperforming pre-mades, the underperforming people would need to be cut out too. If you want the best balance, you'd need to cut off the bottom if you cut off the top.