Or that Medallions are more limited than other forms of Investiture, why would invested forms of Fortune be different, some being better than others, and others showing different points in time?
How are they incompatable? They would just be different kinds and forms, Atium when burned with duralumin lets you see the future in similar ways to the shards, same with electrum.
Aside from stealing the invested art that provides it, my guess would be Chromium.