Of course acknowledging this means acknowledging that sometimes, as a player, you are going to do things that will cause another player pain. We're all decent people. We don't want to knowingly hurt another player. So we claim that anyone who feels a painful emotional reaction to our actions is a sore loser or a bad roleplayer so that we can feel better in assuming that the majority of people can engage in the game without any pain whatsoever, no matter what we do.
It's not an evil temptation (nor the only reason behind it -- most cultures with issues with bleed also have issues with displaying emotion or seeking reassurance) but it is one that divides us and allows for a steady build up in resentment.
After all, while allowing another player to hurt your feelings through fictional actions against a fictional character is often a taboo, being the victim of unfair circumstances is a perfectly valid way of seeking sympathy. Therefore the hurt player has a real incentive to find someone to blame, some great unfairness behind it all, so that they can vent their feelings without being stigmatised.
"Oh, it's not that I'm feeling things, it's that the guy over there actually screwed me over in some unfair way, and the GM's probably in cahoots with it."
Unfairness is something that can net you sympathy card and even if the other players see through your self-deception, they're not necessarily going to call you on it and you never need to admit that the actions were justified and understandable but painful to experience.
NOTE: Yes, sometimes there is some sort of OOC unfairness going on but sometimes it's just a person looking for sympathy who can't get it any other way.
No one's shocked when someone gets upset or angry over what happens on fictional television series, novels and movies. Yet those fictional events are not your fault. You didn't make the bad call that got your character killed. Your friend didn't write the death scene that took out your favourite NPC. You weren't the one sitting in the hot seat while a dozen other people mercilessly point out all of your flaws and mistakes for a full hour in a bid to drop your status and increase their own.
These things are going to be more intense because you're there. The threat of such consequences will also add a thrill to the game, ensuring the successes are all the brighter, so there's no need to get rid of them. It's simply important to accept that the odds of being a person who is incredibly immersed in the experience yet whose emotions switch off the moment something bad happens or someone says END SESSION is incredibly unlikely.
The emotions are there and they will persist until resolved.
Does this mean that bleed is an excuse to be a dick?
However I have found those who own their emotions and accept that sometimes you'll feel bad when bad things happen can actually move through it more readily and with far less (even no) resentment towards those who have caused it. Rather than having to create victimhood narratives to get a shred of sympathy, they can instead turn to the players of antagonists in the game, and to their allies, and go: "Wow. That hurt. It really hurt. I love this game and you guys are all awesome … but wow. Feeling so much more bleed right now than I thought I would."
This then allows the players of their antagonists to give them a hug, metaphorical or otherwise, and talk them through it and maybe provide some perspective. Nothing kills OOC blame on a player of an antagonistic character like when that very same player provides much needed comfort and reassurance.
Does this mean that there are no ways to reduce player bleed or strengthen the IC / OOC barrier? Sure there are! Heck, acknowledging bleed strengthens the IC / OOC barrier just like the example where one's characters are at war while the players help each other out.
Unfortunately most methods to reduce bleed will reduce *all* bleed. You can't get tonnes of the good without the risk of the bad because the more immersion, engagement and attachment you have the worse you'll feel toward loss and humiliation -- except by removing the threat or reducing the extent of that loss / humiliation (i.e. cooperative PvE game where no loss is permanent).