My understanding is there was a group that was saying to combine stuff by use. So you have a class to determine total price, but you sell liquids priced by liter, gasses sold by cubic foot, and solids sold by quantity. Each of those are controlled by separate departments and require different methods of calculating price.

DDD basically says to group everything for liquids together, everything for gasses together and same for solids. Don’t group by process but by who uses them.