Unless you have rocks stuck in the seasoning, neither polymerized oil nor steel is hard enough to scratch it. They literally can’t.
this is not actually true. There’s still wear to the harder material. The harder material still wears over time, though less so. also: from proline:
One of the most common causes of scratches on induction cooktops is rough-bottomed saucepans and skillets. If you are using a pot or pan that has a rough surface on its base, it may cause scratches on the cooktop.
Most manufactures will also recommend not using rough bottomed pans. (or placing something under it like a cotton pad/cloth), it’s literally one of two warnings against cast iron (that, and weight.)
Also, part of why that is, is that the rough surface does trap things (like carbonized foodstuffs.) which act like grit. a polished surface is much less likely to trap such things.
and again, it makes the shake-pan-to-stir thing (like you see for stir fries or flipping omlettes and pancakes) easier with cast iron.