A. it's a layer of burned, polymerized cooking oil. It is in fact a plastic. It is not particularly better for you. It's only non-stick in a weird sense that anything else that hasn't been cleaned is non-stick.

B. it does not really prevent rust - if it did, we would use this instead of rust protectants :)

C. Cast iron, unlike steel, generates mostly dust when it abrades. It is often machined dry with vacuum because it otherwise clogs up coolant systems (it makes a sort of mud).

The dust is very bad for you. So everytime you scrape through that coating and abrade it, or microabrade it, you are probably getting cast iron dust in the air/lungs.

I'm sure this will end up studied post PFAS and will be discovered to have been a similarly bad idea.

Use steel - it "seasons" just fine (it turns out burned cooking oil will happily stick to lots of things), and doesn't have this issue.