There is a big difference between servers and desktops.
For *most* people they want their server 24/7. Just the way it is. My server here runs my network. No server, no DHCP, DNS, mail, and a lot of other things besides. It is busy most of the day and night - it runs sync and backups & other stuff over night.
If you look in servers settings there are plenty or energy reducing options like throttling CPUs, more efficient CPUs, better thermal efficiency etc etc, and then you have bigger denser drives, and now Solid State drives etc etc. They can slow themselves down and reduce energy a lot without needing to be shutdown.
Computer hardware is not at its best being constantly turned on and off. Much better to be running at a nice stable temperature. The constant temperature changes will affect the hardware and reduce the lifetime, or increase the risk of failure.
It is much faster to wake it up from 'resting' rather than 'sleeping' or 'dead'.
Yes, perhaps you have a backup server that has one function once a day. But that is a specialised machine. It is a simple file store and has none of the normal server functionality (think of it as a complicated network attached drive).
A normal server is multi function. It is a complicated beast running many different tasks. Not the same thing at all.
Notwithstanding this, the point you have missed which I have said previously is that WAKING a machine is NOT the job of the OS. That is a function of the BIOS and/or network card. The OS only takes over once the machine has started, and not before. So that has nothing to do with the OS and it is something that has several easy solutions.
Shutting down is another matter entirely. You can easily script that to do so at a fixed time. The complication is if you want to shut it down when it is idle. What is really 'idle'?
Desktops work that out by keyboard and mouse activity. How do you do that on a server that has no keyboard and mouse connected (mine do not.....)?
How do you also tell it to wake again? It can't detect a keyboard and mouse that are not attached. WoL doesn't really work that way - please have a read about it. As I said above, it is a function of the motherboard and network card, not the OS. Yes, you can set WoL on a network card with Windows, but in reality you are setting a hardware option in the card and Windows will know nothing about a WoL packet waking up the card. If you had the right piece of software you can set it without Windows at all.
https://www.lifewire.com/wake-on-lan-4149800It doesn't matter what operating system the computer eventually boots into (Windows, Mac, Ubuntu, or another Linux distribution), Wake-on-LAN can turn on any computer that receives the magic packet. The computer hardware must support Wake-on-LAN with a compatible BIOS and network interface card.
So the point is you are looking for a simple solution to what is actually a complex problem, and most of which has nothing to do with SME.....
And that is why you cannot find an answer to your question!