You already lose time and dignity when you fail a key. If keys never downgraded a level, then you’d simply try again until you hit a wall. Maybe a 20minute cooldown or something would stop players from giving up at the first wipe. Overall, players would reach higher ratings and key levels, but the new high would in relative terms be the same as everyone is higher.
Except they could actually push more difficult content upwards as opposed to wasting time upgrading keys.
edit:
might have a downside to the keystone lvls available in group finder. maybe the keys could crack after 2-3 fails instead of right away
it could also take away some of the “meaning” as in “this is it, one shot on opportunity” when doing a keystone
They should make it deplete only if you leave to many m+ dungeons the more you leave the more it depletes, if you leave once it does not deplete, if some one else leaves it does not effect your key.
Also if you leave some one else key it removes a charge from your own key, so your own key will be more likely to deplete.
On top of that if you leave to many m+ for the current week you are getting no vault rewards and instead get coal, and to get rid of the coal you must not leave a single m+ on the next week failing to do so will lock you out from vault rewards until you get rid of the coal.
Also you can get 1 coal a week by simply leaving to many m+ runs.
Also a hidden mechanic should deem when its oke to leave a m+ or not, this is decided by devs not players.
The 2850 and 12+ depletion prevention thing is bs and they (should) know it. 80%+ of the playerbase doesn’t make it that far, if at all. This should apply to all key levels as the real clown fiesta happens on the lower/mid keys.