I read this book as a kid, it changed how I view the world and I've never forgotten it's lessons. It shows how the ad world is working hard to persuade you. It convinced me to always question what are represented as facts by ads or the media. A healthy skepticism has served me very well.
Most people never deeply question and Packard is correct that there's an entire industry trying to persuade you. Not just what product to buy but which college to attend or which company to work for and yes even which political candidate to vote. Those very same hidden persuaders, some of the brightest minds in the world, are working on the web still trying to persuade you to click.
The closest way to bring it to HN world is PG's famous essay The Submarine that talks about recurring themes in the media such as 'suits are coming back'. The public relation professionals planting those stories are also hidden persuaders.