...The system stays in the active mode (with the screen off) for a longer interval of time. These longer active intervals occur for a variety of reasons, for example, processing incoming email or downloading critical Windows updates. Windows components that are allowed to leave the SoC in the active power state are called activators because they are registered with the power manager as capable of blocking the transition back to the idle power mode. The durations of these activities vary widely but are controlled to extend battery life.

Switching between S3 and Modern Standby cannot be done by changing a setting in the BIOS. Switching the power model is not supported in Windows without a complete OS re-install.

It is small modern "invention" by Microsoft, so they will be able to send big packets of collected info to OS owners and be able to install most OS updates even if you are unaware. As you can see above - system is made to prevent ability to switch such behavior off. So, remember to always go into hibernation mode if you go to presentation or similar thing, as otherwise you can suddenly see nonfunctioning computer.