Actually - you can put it into sleep mode, and after a while switch to suspend mode (where it dumps the memory content to disk and powers off).
Thing is, as linux boots up so fast, I tend to always shut it off when not needed in the near future anyway. But on my current work dell latitude 7400 device it works pretty well.
To be honest, I think users would boycott Microsoft if you had to reboot your system for AV updates :}
Very honestly, I have one gaming Rig running Windows - all the remaining computers run Linux. I never spent so much time looking at an upgrade screen as under Windows. And sometimes, it is not one but several reboots that are required. And the worst part is: You can’t work on your device while the upgrades are being applied (against downloaded and prepared!)
In my experience linux sleep works well, and windows sleep doesn’t exist. The difference between linux and windows sleep is one of the reasons why SteamOS on the steam deck is a much better experience than windows on a handheld (among plenty of others).
One anecdote to moderate your expectations: on this 11th gen Framework 13, if I use “deep” sleep and only connect USB-C expansion cards, sleep basically works, draining in the vicinity of 1% to 1.5% battery life per hour. It wakes up reasonably fast, with a delay (10 seconds? something like that), how computers used to be.
If I do anything else, standby is a disaster. Battery dies way too fast. This is still an improvement on the Windows laptop I got from work, but that’s not saying anything.
I’ll note here that hibernation in my experience, is not necessarily as reliable. Sleep stores system state in ram, and hibernation stores it on disk for further reduced power draw and stability. However, I cannot reliably resume from hibernation on my machine thanks to a bug between the linux kernel and the ssd’s firmware that results in the hibernate partition not being discoverable sometimes on power resume.
I believe windows has also moved away from using hibernate and disables it by default now.