Board Game Arena

Is there a reason for this?

If not it is just an absolute waste of everybody's time. When the game is clearly over for me, i should be allowed to concede. And in certain tournament formats that also creates problems/disadvantages for the winning player because they may miss out on getting enough games in to get extra points.

In some tournaments, game-score-difference is tie-breaker when getting from stage 1 to stage 2. Conceding would be messing with those numbers. Maybe that's the reason.