Platts just redefined European oil pricing, and it did it with a single line: Russian-crude-derived fuels are out. Beginning Dec. 15 for cargoes and Jan. 2 for barges, any diesel or other oil product that can be traced back to Russian crude will simply not count in the assessments that shape benchmark prices across the region. If that sounds wonky, you’re not alone. This is a material shift in how one of the most influential price setters on the planet defines supply. Historically, Platts has been product-focused. If you offered a cargo of…