Immersion cooling was/is so fucking impractical it is only useful for very specific issues. If you talk to any engineer who worked on CRAY machines that were full of liquid freon, they'll tell how hard it is to do quick swaps of anything.

Its much cheaper, quicker and easier to use cooling blocks with leak proof quick connectors to do liquid cooling. It means you can use normal equipment, and don't need to re-re-enforce the floor.

A lot of "edge" stuff has 12/48v screw terminals, which I suspect is because they are designed to be telco compatible.

For megawatt racks though, I'm still not really sure.