See Title. They're understandable, necessary, and even unavoidable at times. Nevertheless, they ruin everything, at least in multiplayer formats. I just finished off an extended and enjoyable Commander game...which ended far sooner than it should have, thanks to concessions.
It started off simple enough, with a nice four-way dynamic going on. My opponents were running Kresh the Bloodbraided, Mayael the Anima, and Vorosh, the Hunter. The Kresh and Mayael decks were fairly standard, and the Vorosh deck was really quite scary, gathering an insane amount of mana very quickly to ensure nigh-endless Vorosh replayals when (not if) he was removed as often as possible.
Things went fairly well, swipes back and forth, with some scary plays on all sides. An early Lurking Predators from Mayael nabbed Eternal Witness and Windbrisk Raptor on the first two tries before meeting a Wickerbough Elder; the Raptor met a Putrefy. (Both from Vorosh.) My Future Sight met Mayael's Acidic Slime, and I retaliated with Cloudchaser Kestrel to remove Where Ancients Tread. Vorosh dropped sooner than something that scary has any right to, and was followed by Mindleech Mass. And the whole time, I was sitting there with a Mass Calcify in hand, just waiting for my chance.
I should explain. I almost never get to use Mass Calcify to any good effect. It's my deck's sole piece of mass creature removal, because everything else was too expensive for my tight budget at the time I was building the deck. Suffice to say there's a reason for the low price. Almost without fail, there is at least one other player using white creatures, or I have key nonwhite creatures on the field (Magus of the Future, usually), or my opponent's creatures have some form of regeneration or indestructibility, or I just don't have enough mana to use it. Often more than one of those conditions apply. So when I see an opportunity to use it, I'm pretty excited.
Then Vorosh uses Necromancy on the Windbrisk Raptor. Dangit. And Mayael's player uses Congregation at Dawn to tutor up Duplicant and Akroma to deal with Vorosh. Drat. Mass Calcify is once again going to be ineffective if I can't deal with those. Kresh drops, and Vorosh is recast.
Mayael's player makes a really neat play, Hymn of Rebirthing my previously discarded (thanks to Howling Mine) Dust Elemental to return his own Witness, Duplicant, and Slime. Slime kills the Necromancy to stop the Raptor, Duplicant kills Vorosh again, and Kresh becomes ridiculously big. (More use than I've ever gotten out of the thing--I don't even know why I keep it in my deck. Inertia, most likely.) Mayael finds Godsire. (Dangit, Mass Calcify!)
I cast Body Double to get my own Raptor to fend off Mass and Akroma, and already control Purity. I also drop Isperia, Sacred Mesa to negate the Sire, and Colfenor's Urn--someone at the table has got to have mass removal, and I want to recover quickly.
My prediction proves accurate, as the Vorosh player casts Damnation in short order (Setting off a ridiculous number of triggers for a Kresh that is no longer around. But that's a rant all its own), with Vorosh to back it up. Urn ensures my recovery, and thanks to Body Double I now control a Godsire. Thanks to my inattention when resolving Urn triggers, Dust Elemental comes back, too, though, forcing me to return it and my Purity to hand. (I used the Mesa to avoid returning more.) Why do I have Dusty in my deck, again?
On the plus side, yay! Mass Calcify might be useful again! Until Mayael's player drops Witness to recur Akroma. Dang. I so need more removal in this deck. But I'll be able to attack Kresh's player next turn and be sure to hit, thanks to a glimpse from the Mass!
That's when it happens. Just before my turn, Kresh's player apologizes and concedes. Well drat. And not even because he really had to go, but because he was mainly out of gas and didn't feel he'd be doing too much to affect the game. Dangit. A hit with Isperia would've allowed me to tutor up Blazing Archon to stop Akroma, or Glory to fend off all comers, or any of a bunch of other things. But I suppose it's not to be. My Body-Double-sire dies a gruesome death in short order, and things fall into a stalemate between the remaining three players, with Vorosh and Keiga on one side, Akroma on another, and my Mesa, Purity, and Isperia on the last.
I draw Condemn, one of my very few pieces of removal, and perfect for Akroma. I mostly tap out that turn, and the Mayael player takes advantage of the seeming Pegasus-less opening to attack with Akroma (whose first strike would mean I can't kill it on the block). Ha! Gotcha! Condemn! Now what'cha gonna do? He has no other fliers, and another hit with Vorosh will kill him for me with General damage, and then Mass Calcify can sweep Vorosh's board off the table, allowing win by overwhelming Pegasus-and-Purity army. (Crystal Shard will protect me from Keiga's death-trigger.) On my turn, Mayael plus Rings of Brighthearth finds Hateflayer and Flameblast Dragon--I guess he'll live another turn, at least.
Then Vorosh's player concedes, pleading kid issues. And the game takes a turn for the worse for me. I can't really stop the Mayael player. Not right now. Not like this. I'm not prepared to suddenly be facing him alone--I thought I'd have more time. But I don't. Mayael's player attacks me with Flameblast, targeting Purity and forcing me to bounce it; Hateflayer hits me for ten thanks to Rings of Brighthearth. And then Mayael (plus Rings) finds Blazing Archon and Spearbreaker Behemoth. And Relic Crush comes out from under a Hideaway land to kill off my Mesa. Dangit.
Without another player to encourage restraint, to provide another target, Mayael's army simply rolls over me. With more time, my Mesa would have given me a lot of potential blockers to stall the game. I could have dropped my Azorius Guildmage and used that to stop the Dragon and Flayer both at once. I could have bounced and countered the Archon, tapping down blockers with the Guildmage. But I just don't have the time I need.
Concessions ruin everything. (And yes, I realize I'm whining, but it's a therapeutic whine.)