Earlier quoted context omitted.
The idea of the assassination marketplace as I see it is to provide some means to balance the power of politicians. There's a powerful asymmetry at work in politics. Prosecutors can knowingly wrongly convict people and face no consequences. The President can authorize a temporary (or perhaps not temporary) war possibly resulting in thousand of deaths and the worst outcome he faces for it is not getting a second term.…
Why a marketplace, though? One can already organize resistance against a regime one considers harmful enough to merit violent resistance, via militant groups. They can be right-wing groups like the militia movement or Greece's Golden Dawn, or left-wing groups like the Black Panthers or Germany's Red Army Faction. They do at various times assassinate prosecutors or politicians. An assassination market seems to change…
Because successful states (i.e., not Greece) have vast amounts of institutional knowledge and training on how to infiltrate and destroy radical groups in the embryonic stage. There will never be anything remotely like the Red Army Faction in the USA or Europe as long as the FBI still has any amount of funding. Or even local police, for that matter. In the US, virtually every dissident group is guaranteed to be monitored by police, if not actively infiltrated. It's hard enough to organize unpermitted protests, let alone jailbreaks or breakfast programs.
Assassination markets work around this by reducing the need for organized groups.