Premade groups are ruining battlegrounds...

... do they? I think so. It's no fun to deal with one or even two premade groups in battlegrounds.

Why is there no option to prevent this? 1 and 2 players should count as "single" and 3 and 4 player groups should count as group and be treated as such when it comes to matchmaking.

And no, it is no solution to counter premade groups with the argument "go look for a group yourself".