I am glad you asked that.
As you should know by now, passive 2-phase immersion cooling is one of the most elegant ways to cool. Now compare that process using 3M Novec Engineered Fluids with their low boiling points (ie. 34C or 49C) with a simple mineral oil bath, which is thick and greasy (oil is a high viscosity fluid) and doesn’t boil. It performs better than air, but due to its physical limitations it will never get close to evaporative cooling (aka "phase change cooling", "2-phase cooling" or "multi phase cooling") we use in our systems with Novec fluids.
One of the great advantages of passive 2-phase immersion cooling is to reduce mechanical infrastructure, while oil actually adds new points of failures to the equation (see our more formal FAQ here). Our tanks are literally silent, dust free, and don't have any moving parts. We don't have pump stations next to our tanks, and no oil means we don't need secondary containment tanks around or under the tanks due to safety regulations. Did I mention that Novec is non-flammable and used as green fire extinguisher at really important data centers (stock exchange)? Or operating theaters, where you don't want a sprinkler system to go off during surgery?
If you have immersed a motherboard with CPU into an oil bath, you probably realized that without pumping and moving the oil, it doesn’t take very long for the CPU to overheat. While oil is somewhat better at transferring heat than air, it is unfortunately also incredibly good at storing it (that’s why you find oil in oil radiators).