I don't think that poster misunderstands what is at stake. It's a generalization, nothing more, nothing less. The poster he is replying to is like a moth to a flame in the sense that the same way Hitler youth were. They carried out the commands of the leader and thought that it was the right thing to do.
For them, it wasn't a matter of introspect or human nature, it was a purpose, a reason to exist. That's why the Nuremberg trials went like "I was just following orders".
We are on a slippery slope and I don't disagree with the comparison. If you can't see that coming around the bend then it's too late for you as well.
Ideologies are one thing and honestly, there's nothing else to compare what's happening to this country now other than the Reichstag. If you want to blister people for talking points, you best look in the mirror before trying to understand it.
Most of us are not Jewish and never read the diary of Anne Frank. Never lived the life of Schindler's list but anyone who has should see the writing on the wall. This is a five alarm fire my friend. They are disappearing people again and their cheerleaders should be called out for it every single time.