Because democracy is a key part of Marx/socialist thought. The whole idea is that collective ownership of capital would mean it would be democratically managed by the working class, for the interests of the working class, rather than for the interests of someone else. You can quibble about that if you want but it's a big part of socialist thought anyways. It's only in the modern period that democracy has become synonymous with the western capitalist system.

So to what extent is democracy MORE a socialist thought with regard to its respect and enforcement of socialism than is the Western Capitalism system to which its become more Modernly and Popularly associated?