The issue with these sumerged coolant pc's is that you wind up cooling things that have an enormous heat dump but are perfectly alright running at 100C.
Note the voltage regulators on graphics cards and motherboards.
Do they run extremely hot? Yes but their high temps are well within operational limits and as such don't need to be actively cooled.
With a submerged oil pc your cooling things you dont need to, and as a result your getting a lot of heat dump into the system that isn't beneficial o performance.
Because water cooling focuses on just the parts that matter. (CPU/GPU cores, Mosfets, NB, Southbridge) It is able to focus all it's cooling power on those parts.
Plus looking at the radiator in the reactor that looks to have about the surface area of a single 3x120 rad. And they are cooling a quad, 3 gpus's and every single other thing that produces heat with it.
For the same price as the reactor I could build a Mountain mods ascension duality build with two full pc's inside and a thousand dollar water cooling setup.