While your point is taken, it's worth noting that when discussing the dark side of empathy, coercion and emotional manipulation the 3rd Reich stands out by any standard. Hitler paid a lot more regard to propaganda than anybody else on the world theatre - Waffen SS uniforms were designed by Hugo Boss. Leni Reifenstahl was given a nearly unlimited budget. Stuka dive bombers were outfitted with noise-makers on their landing gear so the Allies could hear them coming (and be afraid). The Me 262 - a high-speed jet interceptor - was pressed into service as a light bomber (a role it sucked at) so that the Allies would quake in their boots against superior Nazi technology.

If we're taking about the downside of propaganda, you're pretty well obligated to mention Hitler, who often favored propaganda over tactics. Aside from arguably the most shocking perpetration of crimes against humanity in the history of the world, the Holocaust was also a dire logistical drain. Godwin's Law certainly, but Hitler ain't exactly six degrees from this discussion, if you know what I mean.