Actually, that would only be right if the Raspberry Pi was any good regarding power usage. However the Raspberry Pi is utterly crap at power savings, with practically no power saving modes and very power-hungry (though cheap) components. (excluding the RPI0 models, which have no peripherals whatsoever).

I have a _very old_ PN40 from Asus -- this is a full PC with an intel Celeron, a SATA SSD and about 8GB of RAM that idles at 1.7W (serving websites via GB Ethernet) as measured _at the wall_. This is just standard PC Linux distro with zero customization (other than `powertop --auto-tune`).

For comparison, the latest RPI4B without the SSD and with 1/8 RAM idles at 3.5ishW on the wall. Even the older RPI3 I could never get below 2W, and that is without any peripherals (no display, no Wifi, no eth, min USB) and significant tuning.

On the other hand the PN40 + components cost significantly more (probably close to 10x), and the CPU performance itself is not that good these days.