"World War III will be a guerrilla information war with no division between military and civilian participation." - Marshall McLahun
I noticed it during the 2016 election. My Twitter and Facebook accounts were awash in anti-Hillary comments. Many comments seemed to piggy-back on my own reservations about her. Other comments were wildly inaccurate and mean-spirited.
I was a Bernie supporter and not happy with the way the DNC and Democratic leadership conducted the primaries. Still, Hillary Clinton seemed the better choice in my view.
When anti-Hillary tweets and messages mirrored my concerns I sometimes "liked" the comments or added my own to support of my views. But then there were many outrageously false anti-Hillary claims. I mostly ignored these, but sometimes took issue. This often led to debate with some implacable troll on social media. I engaged them not to change their minds (impossible), but to make sure others would be exposed to a reasonable set of facts.
During these internet encounters I noticed a lot of respondents chiming in with "likes" or retweets supporting the opposition side. The longer the debate, the greater the number of these silent opposition supporters. sometimes as many as 20 or 30 different accounts. Some mute retweeters even continued to pile on days after the conversation ended, and they latched on to randomly stupid or other statements made by the original Hillary hater.