Contributing your best effort should be an automatic behavior. To play detrimentally to your group because of laziness or apathy is to be selfish and not a team player.

In the JP community, it's expected that everyone do their best and put the group's interests above their own individual interests in most cases. In the NA (&EU?) community, the fact that this is up for debate says a lot.

No one should tolerate a dead weight teammate on anything in life. If you do this in the workplace, you'll quickly become frustrated as a useless team member gets equal or in some cases more credit than the hard workers.