Well… not everyone was raised to be pro-slavery and many people hated the monarchy. It is naive to think that the way one is raised has no sway in the way people end up being. The way and ideas people grow up with shape the way one thinks. Sure, many overcome it, but many don’t. And the more propaganda increases in the future, the harder it will be to pierce through the eco chamber.
You missed the point. People back then didn't get raised with liberal values like we do now, and yet we now have those liberal values widespread. People weren't raised irreligious and yet atheists proliferate. Reality and especially the crushing reality of Capitalism often radicalizes people away from their childhood propaganda.
I think that I am just skeptical since I have a lot of religious right wing family members that no matter how much capitalism and their country kicks them to the floor, they still spout patriotic, religious, homophobic, transphobic and class traitor nonesense. And from my own journey to leftism, it takes a lot of effort and education to reprogram a brainwashed mind.