2-phase immersion cooling does a much better job at cooling electronics, at much lower cost with less resources. Because of the physical limitations of oil and cooling, high density as in 2-phase immersion would simply not be possible.
Oil cooling is a single phase process. Oil cooling systems are not passive, it requires hydraulic pumps to take hot oil away from hot spots because oil is a fluid with high viscosity. Passive 2-phase immersion cooling uses fluids with a very low viscosity just like water. This means the liquid circulates passively, taking the heat away efficiently without any pumps. Oil needs filtration and treatment and has a limited lifespan when used for electronics cooling.
The engineered fluids in a passive immersion system are inert, have a shelf life of 30 years and show no degradation after long term use for cooling. While the fluid is not particularly hot (ie. 34°C or 49°C when it boils), the constant boiling and condensation is a distillation process on its own. It's also very clean (not oily or greasy), has zero ozone depletion, very low global warming potential, and it is the best fire protection one can imagine (Novec 1230 is state-of-the-art data center fire protection).
Using large amounts of oil in a data center brings non-technical implications since oil is classified as dangerous and flammable. Government regulations, fire safety standards and insurance risks all require careful considerations.
Oil cooling can reduce electricity bills and the burden on the environment. However, in an oil cooling application fans and air filters are replaced with hydraulic pumps and oil filters, while passive 2-phase immersion cooling simply eliminates these resource hogs altogether.
Technically and physically, passive 2-phase immersion cooling is way ahead, and practically we believe the same is also true.