LW and related blogs are basically spoiling fantasy fiction to me. DAE have an experience like this? How to overcome it?

My formerly existing but weakly skeptical atheism and generic anti-supernaturalism got really strengthened here. I bought into the idea that the supernatural means the propositon that some mental things are are not reducible to nonmental things and from that it is only a small jump to say that mental things are entirely in the map, not in the terrain, it is a useful shorthand model to think of some things as mental but they are never irreducibly so in the terrain. So irreducibly mental things i.e. supernatural things are always, in principle, map-terrain mistakes. So we can on the map level think of medicine having healing properties, because the effect they have on a certain condition is what we put into a mental category of making us "healthier", but the medicine does not actually heal bodies, it just changes bodies. From this viewpoint, a Potion of Healing is map-terrain mistake, as it suggests a substance could have a real healing property. But healing is a mental property, a property of models, maps, not real things. You could say the same about a magic sword that has an bloodthirsty evil spirit in it. The real world has only change, certain things can effect certain changes, but it is entirely a mental model that we call that change helping, harming, healing, good, evil, cruel, nice, killing, purifying etc.

Sh1t, now it seems to me the single most important step from the medieval-alchemical world to the world of science was understanding the map-terrain problem! That a Philosopher's Stone (which does not simply turn lead to gold but improves everything) cannot exist in principle and not just empirically doesn't, because the idea of improvement itself is a mental category that does not exist in the terrain!

And now my beloved Dragonlance novels feel utterly stupid to me.

(Note: I haven't read HPMOR beyond the first few chapters, the conflation of the two worlds, rational and fantasy, made me feel uncomfortable and dizzy somehow.)

For fun, what is the worst fantasy or other fictional offender of mistaking mental phenomena for something essentially real? My proposal: the ideas that goodness or evil are substances and they can formed into magic objects such as sword made of pure evil. Not sure where I've read that but pretty sure some novels proposed something like that.

If you can recommend any further reading even if only tangentially relevant to what I wrote here I will be grateful. Am I no the first one to notice the all-improving Philosopher's Stone could not exist in principle because improvement is a mental category and not real, right?