>> I still dont understand how and why liquid cooling could benefits.

Because liquid cooling is only a marginal benefit for current hardware, hardware designed to be air cooled. If liquid cooling becomes a norm we should start seeing hardware designed with the expectation of liquid cooling. That could mean greater component density and greater power concentration --> greater speeds. One wonders what CPUs would be like if they were designed with the expectation of liquid cooling, water within a millimetre from the heat source rather than the metal heat spreaders that currently top most chips.

How many fans are in a modern server rack? Liquid cooling could theoretically replace all of those with one moving part, one pump impeller.