This is a problematic statement. Wealth inequality is not a huge problem. If we removed all the billionaires, people who are currently starving or unable to get clean water would still be in the same situation. Getting the base level of human condition up is the important thing, and it generally occurs much more in systems that are not trying to crush people who create vast amounts of value.
> as far as I can see any kind of arguments against tackling it such as 'we'll miss out on innovation' are capitalist propaganda. This is why it would be good to have accurate historical data to respond to these kind of arguments.
I don't see why this is the case. If you let people take more risks and try more things, with commensurate value exchange to the value they provide, then more things will appear. That's just normal.
You can see it in the small even - if teams are allowed to fail and succeed by taking risks, then they will take some risks. If they are never rewarded for succeeding, or even punished for succeeding, then they will never try.