Almost a bigger threat than astroturfing is biased parties, be it brands or brand managers, taking over as moderators to sway content and suppress content they don't like. Happened in a bunch of artist and influencer subs.

I'd say it failed in that it became an echo chamber - there isn't real public to shape. It would have probably been more effective if done a bit more subtly, which makes it scary to realize that 'effective' propaganda looks like open discourse to the average user.