Well, no system is perfect, but I actually found the opposite. As a templar in EQ2 I routinely helped out others, just for the sake of being nice, and because of the locking system, it was understood as a nice gesture instead of an attempt to steal a kill.

In Gorgon right now, you can "help" somebody, but if you do more damage than them against a solo creature, you stop being a helper and start becoming a kill-stealer. And since XP is split right now, many players will resent your "help" because you're inevitably slowing down their leveling.

I guess the bottom line is that the current system is obviously not going to cut it in the long term because the loot system heavily rewards mega-groups. Mega-groups are actually really boring, even if the rewards are good. It's not healthy for the long-term of the game. The best system I've seen is EQ2s. If you have other systems to propose, that's cool and I'm all ears! But we can't stay with the exact system we have now forever.