This happens when people start to raid, or start to encounter boss mobs that require or have a DPS check. I've seen it happen. I have friends in game an they are not very good, but I loved playing with them. Then it got to a point in the game where you've have to have 6 people who were maxxing dps, so my friends stopped getting invited to groups. Thats the same point when LFG tells started having requirements.
Make it so boss and raid mobs don't have DPS checks and dont require perfect execution of dps abilities to win.