There is certainly a debate over which parts of advertising work most effectively, however I have never heard anyone seriously suggest (until maybe now) that the entire concept of advertising may have no effect at all.
However, I don't think that advertising is enough to remove the democratic component from capitalism.
If you want a perfect example of this, go back to the start of modern advertising and look up the phrase "Torches Of Freedom" and Edward Bernays.
In what way did this harm democracy? Cigarettes are dying off, because of scientific discoveries, if anything this demonstrates my point.