What's "astroturfing"?
The idea is to make it look like support for/aversion to something is organic and popular (grassroots) when it's entirely artificial (astroturf)
The key characteristic of astroturfing is that it attempts to influence public opinion by presenting a false picture of the current public opinion. It's both of those things together that make something astroturfing.
> the deceptive practice of presenting an orchestrated marketing or public relations campaign in the guise of unsolicited comments from members of the public.