Faking activity to bootstrap real activity is probably fine. To expand into international markets, they need to present existing activity to draw and retain users. But I don't see a problem with this.
But when the actions are done in an attempt to trick individuals weighing financial incentives? That becomes much more murky. Had they bootstrapped these communities prior to the IPO filing? Fine. After the spotlight is on them to prove organic growth for the IPO? Murky.
Strong disagree, reading such things habitually is corrosive to the mind and turns people bitter. For reddit to recommend and promote ragebait subreddits to their user is deeply unethical. And to create fraudulent ragebait content, to make people vicariously mad about something that didn't even happen, is evil on par with being a tobacco advertiser.