It's not a Mac compulsion. Have only been on this side of the fence for a year myself. None of the old timers would recommend shutting down any computer. Has to do with the stress caused by expansion and contraction when powering on and off your system. During the 80's, most techies felt your rig would last longer and have fewer hardware issues by keeping it running all the time than powering it off and on. While probably not nearly the issue today that it was back then, very few from those days have changed to a habit of shutting down.
I am one of those. None of my rigs are ever "shut down" unless we're leaving the house for a few days. Have never practiced shutting down a system. My XP machines go for months without being shut down. Would guess that my wife's XP system hasn't even gone thru a reboot in over a year (she never does any updates, and it's been that long since I've touched it).
Most don't believe the parts we have today are as sensitive as they were. But still, why shut down and have to wait for the system to reboot? Yeah, for those greenies out there, you can save a few pennies. But don't think you'll find too many people (and probably no long time tech head) that would recommend you shut down if you're turning it on and off several times a day.
