Poor logic. The existence of propaganda working does not require concentrated wealth. It simply has more interest in it currently.
For example many players in the civil rights movement were not wealthy and did “good” propaganda which others refuse to call it as such.
The prohibition movement was a second example.
It doesn't require concentrated wealth, but if wealth is evenly distributed, then presumably the power to apply propaganda is also equally distributed. Propagandizing information effectively become a meta-level form of voting. With concentrated wealth and power, those with all of the resources hold all of these meta-level votes.