I want to try to fight those as best I can before worrying about being a perfect Marxist.
The problem with this is that it’s very hard to actually fight propaganda without a Marxist understanding of how it works. Just telling people the truth doesn’t really do a lot in most cases. To be effective at counter-propaganda, we have to understand how it actually works in the first place, and theories like ‘brainwashing’ don’t enable us to do that. To effectively fight propaganda, we have to first understand its material origins, relations to different classes, and modes of operation (licensing and bullying rather than brainwashing). These parts are missing from Johnstone’s analysis and that makes her counter-propaganda less effective. This article goes into it in more details, and Red Sails has a whole bunch of articles on the topic.
I’ve never seen her engage with these critiques in good faith. She seems to mostly just get really defensive and refuses to rethink her strategy or the theory in general. A big point here, I think, is the fact that her business model where her readers pay her, reinforces that kind of non-Marxist analysis of propaganda, because it lets the readers feel as an educated and truth-knowing elite above the majority of the masses that are ‘brainwashed’.