You can only concede in a 2 players game.
What you mean is; you can only
quit in a 2-player game without suffering any consequences.
If you quit the game in a 4 players game - you shouldn't do that - and you are penalized for it.
Quitters don't think about the game or any of the other players. Quitters quit because they get frustrated, and they will never understand the game they are playing. I understand it when a player must concede, its quitters that I don't agree with. they make it miserable for everyone.
I've played three games here on BGA, so far. The first game I was losing so bad (I won)! Any normal bloke would have quit playing. In my last game (3rd) my opponent (still had a chance) must have got frustrated and quit.
The object of the game is to play to the best of your ability. If you're in a bad situation, do the best you can in order to survive! You never know when your opponent is going to make a mistake.
I'm sure to acquire many Red thumbs, because I don't quit when those Quitters think I should.