People used to leave their PCs running 24/7 due to the fear of thermal expansion causing hard drive failure. It's not a problem anymore as far as I know, but this practice stuck with a lot of old power users.

It wasn't quite as silly when PCs didn't draw so much power.

The sleep functionality has historically been unreliable at best so that gets avoided as well.

Now, in 2026, even if I'm just going outside for 20 minutes I'll sleep the machine, unless it's doing something in particular.