>It keeps active network connections ...
You can disable that behavior. See: https://www.tenforums.com/tutorials/146593-enable-disable-ne...
That's because the goal is not to have functional hibernation, but to start up faster. If the goal can be achieved by using less power instead of shutting down the whole machine and restoring it identically and that's easier it's a valid alternative.
Interesting. I have yet to come across a computer that I couldn't hibernate in Window.
No, Hybrid Sleep is when the Windows machine goes from Modern Standy to full shutdown and power off.
All laptops support that though it's not always enabled as a feature by default.
You used to be able to edit ACPI tables to reenable S3 sleep but these days they're stripping the functionality from firmware entirely.
For example, HP's enterprise lines have S3 stubs in their firmware. If you enable them, nothing happens, because someone deliberately removed the S3 blobs entirely.
BIOS support for proper hibernation has been getting worse too because with MSFT demanding it, there is little reason to continue support.
I've had older laptops that do the sleep->hibernate setup without too much issue but now it is a crap-shoot on if it is even supported in the hardware.