Should it be allowed to concede a victory with 99% game completion?

[terrrezad]

This has happened to me over the past two days (in three games). I’ve had a lead of 3–4 victory points, and my opponent obviously no longer has any chance of at least matching them. Instead of waiting for the point tally at the end of the turn—for which we only need to pass the turn—they have preferred to concede the game. Even in friendly mode, where ELO points aren’t penalized. You might think it’s circumstantial, but I checked their last matches, they do this regularly.

[Jellby]

Even in friendly mode, where ELO points aren’t penalized.

Even in non-friendly mode there's no elo penalty of any kind for conceding. A concession results in full loss for the loser (and nothing else) and a full win for the winner.