Something I think is missing:

Stainless steel, and other materials that don’t “rust” - eg aluminum, do react with the atmosphere, they just form a very thin layer of oxidized material that is essentially airtight and won’t let the material below it come into contact with the air.

If you remove this oxidized material, say by rubbing it against something very hard like a chain sprocket, the material below will now be exposed to the atmosphere and will almost immediately oxidize, and then that gets removed by the chain sprocket and so on.

The typical approach - use a fairly hard steel that resists being worn down and then making sure it’s lubricated provides better results without going into really exotic (extremely expensive) materials.