No, in any historical system that was neither capitalism nor very small scale society in a very limited span of time, greed, selfishness, and corruption of all kinds was rewarded more than in capitalism. Not always in money, but certainly in inequality of power. Money means only as much as the power it can buy. Capitalism did not increase the inequality of power. Rather, it made the inequality more transparent by giving it a measure.
You cannot meaningfully claim that the ruling class in, say, Cuba, has less relative power than the ruling class in America. Nor can you claim the average citizen in American has less relative power than those in Cuba.
There has never, ever, been anything that actually happened on a large scale that is better than welfare capitalism.
Depending on what you mean by "socialism". If it's led by a vanguard party, then the party controls power and there is your system for rewarding it.
If it's not, well, that sort of system never, ever happened before in any meaningful scale. And communists, including you guys, readily admit you don't know what that system would look like in practice. Which means you cannot assume "there would be no system for rewarding it".