If amplification is really a “thing”, I would encourage you to take a look at Trump’s social media accounts. Most of the posts that show up underneath (replies) are people critical of him. The free advertising he gets across social media, cable news, radio, etc. in this way should dwarf a couple shill accounts. If someone retweets in a forest, and no one is around to hear it, does it make a sound? I would rather give people the freedom and tools to see whoever they want to follow than ban these accounts for “hyperactivity”. I find it hard to believe that robotic posting constitutes a violation of Twitter’s TOS by itself - there’s tons of companies that make it their business model to let you do so!