What's frightening is that groups like politicians, unions, and extreme right-wing groups could very easily use this technique to quickly and pretty effectively promote or quell discussion.

I just recently saw an example of where this might have happened. Very suddenly a comment in a discussion I was following - what initially was a popular up-voted opinion (i.e discussing police brutality) - got down-voted into oblivion (from +5 to -25) in less than 5 minutes. The comment was deleted soon after - probably to protect their score.

This kind of quick/easy manipulation by bots can't be easy to detect/deal with yet I fear it may become mainstream.