It hasn’t been proven, because it hasn’t been attempted. What existed for a short period of time back when the game was weeks old is not proof of anything seventeen years later. CCP just isn’t in the habit of providing innovative design solutions (e.g. look at how stupid “Crimewatch” is).
Lots of options could be attempted. For example, and this is just off the top of my head and spontaneous thinking, all ships could be given a distress beacon button, and an invulnerability core style mechanic. A gank starts to happen, and (assuming they’re not AFK and deserve to die) the target hits the panic button. Now they have a few minutes for someone to show up and try to save them. No one shows up? Oh well, tough ■■■■. Should’ve taken some precautionary steps, chump. But if someone does show up, the odds of the gank being successful decrease dramatically. The protectors can be compensated with a FW-style bounty mechanic, getting a payout proportional to a percentage of the value of the ships they destroy. The viability of this could be compounded by the gankers switching over to using ships with actual combat setups, driving up their costs, and making bigger bounties possible. And finally, if a victim is saved successfully, they should also compensate their protectors with a tip from their own wallet. If someone just saved you from taking a 500 million ISK loss, send them 50 with a thank you note. It’s only fair.
Obviously this system could use more thought than the three minutes I put into it while typing this, but my intent is to show that other solutions are possible.
So a kill trigger, plus profit removal? What’s the point of keeping ganking in the game at all, then? Might as well indeed remove it. This is kind of like the “idea” some people have in which the gank victim receives a payout directly for the value of their loss from the gankers’ wallets. This would eliminate the activity entirely.