If you can rambo and take everything out, then that saves your team mates from dying, your medic from having to frantically triage the situation, and frees up everyone's ammo.
Yes, you save them having to play the game at all. All the stuff you just mentioned is called "playing the game." Some people even dare to call it fun. Please save us from the fun.
We're not all playing in a vacuum - every zombie I kill is one less that could kill you. If I can go off alone and kill them all, then why shouldn't I?
You conveniently overlook the other side of that argument. Every bullet you're not shooting at the specimen attacking your teammates directly is one less bullet they might need when it counts. The game is balanced by the end waves to throw enough specimen at you, you get overwhelmed if people don't have ammo, or if they're not freaking there in the first place. It used to be more of an issue before the update, but it's still an issue and gets more important the higher up the difficulty you go. Total specimen count? Who cares? The specimen in front of me are my immediate concern.
Except they're not there....because you're "helping." So the game becomes sitting there watching the wave count go down, or turning into a rambo yourself just to stay occupied. When the numbers finally pick up enough so everyone gets something to shoot...you get that right combination that pretty much requires your whole team being there or you all die, like 3 Skrakes and 2 FPs coming from multiple directions.
At this point in the game, when level 4 perks are the norm, weapons are uber and people know how to play, you're not doing anyone any favors. They're just sitting there going "where the hell are all the specimen" or dying and wishing they had actual teammates, instead of a guy running around justifying being alone as a good thing.
It's just an extension of the same lone wolf crap people do by default in competitive MP shooters. Sadly, now, everyone has the perks and the kickass weapons so they aren't getting penalized for it anymore. I can only hope we get teleporting specimen in an update, with a tentacle grappling arm.
In our group, the general rule is rambo if you want for waves 1 and 2. On wave 3 and 4, it's time to quit screwing around and play seriously. Sometimes it's worth the effort. Sometimes it isn't. But I know I wouldn't still be playing KF if I didn't have people to play with who took team work seriously.
I guess my real question is this though. Why does anyone play on servers if they don't want to play with a team? The higher HPs and specimen count? If that's the case, TWI should just make a hardcore solo mode with 6-man hps and numbers of specimen. Rambos don't even have to go through the pretense of helping out then, they can be in their own little world.
And I see far more medic rambos on suicidal than anything else. The insane damage soak on the armor keeps the nimble alive the whole match, and they don't have to kite for pure survival as much because of the heals. Add an M14 or a crossbow, and they are golden. Most 'zerkers tend to die when a husk snipes them twice in a row.