When docker first appeared, a lot of people explaining docker to others said something along the lines "It's like a fast VM you can create with a Dockerfile", leading a bunch of people to believe it's actually not just another process + some more stuff, but instead an actual barrier between host/guest like in a proper VM.

I remember talking about this a lot when explaining docker to people in the beginning, and how they shouldn't use it for isolation, but now after more than a decade with that misconception still being popular, I've lost energy about it...