Stuck in their ways when it took ages to start up, these days I can't think of many reasons not to turn it off.
That would be me, on my old system, it would take around 8 minutes for Windows 10 to boot up and finish loading!
I'd power it on, and go make a cup of coffee in the meantime!
This was on a PC that hadn't had a clean install for years, though!
So obviously I used the sleep function.
My new PC boots up and is fully loaded in 30 seconds or less, so I really should just turn it off and on again, but old habits die hard.