Killcams are a masterfully-designed element in TF2. As the developer commentary states, killcams were added due to many Team Fortress Classic players having trouble determining who killed them and what they themselves did to get into that lethal situation. By showing you a quick screenshot of your attacker with some subtle “swoosh” effects showing you his rough location, Valve turned every death into a learning experience while simultaneously lessening the chance the killer can keep farming kills from the same location.

Valve needs to go back in time and give this Pyro a free "Killcam Taunts" Strange part. Picture by lord_beklanaze.
But more importantly it creates amazing screenshots. Picture by lord_beklanaze.

But I’m wondering if that behavior becomes slightly unbalanced in a competitive setting. When you’ve reached the point that all the players are seasoned veterans who know the game inside and out, the killcam is only providing free information that hurts some classes more than others.

"Sniper under the bridge! And he's got a flamethrower!"
“Sniper under the bridge! And he’s got a flamethrower!”

Several classes, especially Spy and Sniper rely heavily on positioning to be effective. Not only does the killcam give away his location, dampening the fact that he out-maneuvered his victim, it also tells the entire enemy team his health and loadout. It’s like the Your Eternal Reward problem but for everyone.

"Don't worry about the sniper guys, he's fleeing the map!"
“Don’t worry about the sniper guys, he’s fleeing the map”

But at least the lone wolves are only affecting themselves; if a member of a group push gets a kill, they may be giving away information on the positioning and status of their teammates as well. A dead player might be able to spot the enemy Medic and notice his Uber is ready. Or that the enemy Engineer is hauling something to a new location. And all the player had to do to gain these strategy-affecting realizations was get killed. It just feels like far too much reward for what should be a bad thing.

Though good luck successfully explaining this kill to your teammates.
Though some information is easier to extrapolate than others.

So just to reiterate: I am not at all against killcams in normal TF2. They’re amazing and I might love them more than anything else in the entire game. But I feel like they are not a particularly balanced concept in a competitive environment which is attempting to reward skill and remove unfair advantages, because a killcam can be far too positive a reward for the otherwise negative act of dying.