Why are people in co-op mode a bunch of jerks?

50% of them don't even accept the matches for some reason (like dude you don't need to have a godly rank player using the lastest unit on your team to win the easiest mode in the entire game), 40% just troll the matches for some reason and the 10% are normal people.

It's not that big of a problem but it's annoying (just like the rest of this game I love)