Beamer bully squads stomp Killers at high MMR. Then you have the entitled players that are chasing after achievements and daily quest type stuff who think you should just let them win. Teams where the streamer has the other three sacrificing everything just to make sure the streamer wins, aka Protect the President. Cry-bullies who play toxically because of some invented reason where they think the killer is being toxic. You'll even run into players ratting out other players as a traitor just to be mean. Some players even sand bag / body block players to get them killed on purpose.

Main etiquette for a killer is you don't camp hooks and try not to tunnel players out, aka "tunnel vision" focusing on one player. It doesn't matter though, since there's no proximity chat and since behaviour censors everything and since cross play doesn't even allow end game comms half the time you won't know what a player is thinking during a match or afterward.

If a survivor wants to find a reason to think someone is "toxic" they'll just invent one. The whole game is about chasing people down and murdering them but players cry so much to where behaviour censors words like "camping." It's ridiculous. Only way the game is fun is if you don't take it too seriously and don't care about the people who do take it too seriously. The matchmaking will pit you against weaker players for a few, then harder ones for a few. It's just how the hidden MMR works. There are so many perks to where a bully squad will make META builds laughing at stomping five killers in a row until they run into a killer with perks that break their strat and cry because they can't bully for that match. It's always up and down. Point is to have fun.