Mostly for not loosing unsavable work across transit. Though, Windows has kinda blurred the line between shutdown and standby, so now you can do neither (I guess you can still shutdown properly holding down the shift key while pressing the button, but who thinks about that?).

But standby was indeed much more prevelant when booting your laptop took 2~5min.

I don’t want to shut my PC down just to walk a few blocks down the road to get lunch.

S3 standby my machine takes 10 seconds to wake up, S0 standby my machine takes 5 seconds to wake up, but to fully boot up from off and reload everything to where I was will take minutes and destroy my poor battery. i9 and nvme ssds are not power friendly.

I use my computer as my main communication device. When I wake it up, I want all my apps refreshed and ready, texts and mail downloaded, and everything ready to go. Then again, that’s why I have a Mac 😂 works great