Playing in a four-man group is a lot of fun. You and your friends, communication, probably some good play…
If you go into matchmaking, and the unsuspecting 5th person you get paired with appears… say something.
“Hey man, we’re a group of 4. If you’re looking to monster, we’re happy to have you! If you wanted to hunter, hop back out real quick~”
It’s a small amount of effort, but it really means a lot. Especially when someone who doesn’t monster actually plays a round (and gets royally screwed), only to find they’re stuck in monster-mode again.
Please, be kind.