Most of the money returned to shareholders isn't going to be pumped back into the economy as money spent on goods and services. It just goes into the casino we call stock and bond markets where it provides some liquidity for some investment into companies, but most of it is just spinning around creating no value.
It matters whether people’s work is effective or not, because it it’s ineffective, you have fewer goods and services that can be consumed.
The factor that connects work to output is called productivity.
It matters how the goods get distributed, yes. But as communism has shown, it also matters a whole lot how many goods and services are being produced.