This really isn't difficult stuff.

Communism is based on worker enfranchisement and abolition of the commodity form. Where is the inherent incentive for autocracy, and what examples would you care to cite?

Capitalism, on the other hand, naturally favours monopoly thanks to factors including economic power acting as political power, first mover advantage, and economies of scale. Capitalism has no inherent need to even be democratic. Your democracy is polluted by economic influence, your workplace is autocratic. What is there to get right that stops any of this?

... But more importantly, how do you oppress everyone in an economic model focused on worker enfranchisement?