On the other hand, if every second house in a large area suddenly sprouted a sign for a candidate, you might rightly interpret that as strong support. Having 10,000 likes on a post is akin to this latter scenario - showing that there’s a whole lot of “actual people” who are on the bandwagon.
Signs don't just grow naturally out of the ground. Someone had to make them and put them there. And those signs aren't there to decarate yards. They're there to convince passerbys that a lot of people support a particular candidate.
If 100 different Twitter accounts all weigh in on a thread, arguing for one side, but they are all secretly controlled by one person, that creates a false picture of widespread support for that person’s stance.
It’s true that traditional advertising has always been used to create artificial buzz around candidates, and this is often a bit manipulative. But creating a crowd of fake supporters, with fake photos and bios, and deploying them in conversations with unsuspecting real humans, is a whole different level of manipulation.
If this is true (and I'm not saying it isn't), the entire premise of Democracy is incompatible with modern technology. We could keep trying to bandage it with "fake news filters", but at some point we will need to admit defeat on that front and start fiddling with suffrage rather than fiddling with free speech.
Paid celebrity endorsements on TV like we see for products are the same. I don’t know if you can legally do that for campaigns, but you could definitely hire them to the staff as a surrogate (any rules against doing so at an inflated rate)?