Because of mechanical wear and tear in traditional hard drives and fans, I've never really liked turning off my computing devices. A steady on state is better for the hard drive in the long run.
Just like constant highway drive, stop and go traffic is bad for your hardware. However, all the concern these days for being green and conserving resources have caused me to slightly change my computing habits. Now, I make sure my displays are off before bed, but I still leave my desktop and laptop on almost all the time. The desktop is even protected by two massive UPSes from APC, just in case there's a blackout.
Still thought, I like my equipment instantly accessible at all times.
The question of the day is: Do you turn off your PC at night?
thus my system is on 24/7 (most of the time..)
1.5kVA UPS makes it easier to keep the system on while I am not around.
A quick reading of the article would have shown you that Tuan was referring to hard drive wear and tear, which is definitely a factor for people that turn their computer on/off every day, especially since those are often the types of people that not only turn it off at the end of the day, but also turn it off any time they're not using it.