surely these kinds of tactics only work on "dumb people" right?
The insidious nature of propaganda is that it works on everyone if done right. Even the people who are responsible for knowingly push it to some extent. Architects of this stuff purposely seek out true believers to act as ministers and soldiers in their psychological war because they are the best at proselytizing and convincing persuadable people to join a specific in-group.
I can't sit here and not feel I've been manipulated in a specific way on say social media. When you get angry at a news article and click an angry face, you've given the machine another data point to build a profile of you and then target you with very specific messaging to manipulate you.