I have a working mental model for how electricity works that is useful enough to let me do (some) electrical work, figure out simple electronics circuits, have some sort of understanding of how electrical devices like light switches, light dimmers (of the mechanical and the electronic kinds), motors, batteries etc work, ... All of these are useful skills.

Yet I know for sure I do not understand electricity, as I do not even understand most of the answers given to me when I ask about whether electricity has mass. And, apparently, many people who claim to know about physics don't either, because I get all sorts of answers that contradict each other.

Should I not know what I do know about electricity because my mental model is a simplification? I think your position is needlessly absolutist. I don't think my teachers ever taught me 'junk', just a (useful) simplification/model of reality.