Water cooling is just air cooling that moves the fan. If you have a crappy radiator, you aren’t going to get great cooling. Water is a great way to move heat, which is why we use it for cars, heating, and power production.

I wouldn’t cite LTT for much, but IIRC, that was only true to a point. The NHD-15 is great, but a lot of cases can’t fit one. Same with many other high end air coolers. It might also cool to the same temperature, but is also running the fans harder to get there.

The entire computer is throttled into a power consumption you can sink through air coolers. So, unless you are overclocking something, it should always be enough. That will hold until companies start to design the components specifically for water cooling.

But the people claiming it can be quieter or thinner are quite right.