The same theory applies for pro PC gamers, an unusually high amount use $10 microsoft optical mice. Then there's the majority of casual players arguing over the details of the latest $90+ mice with bells and whistles.
I actually had a good reason for keyboard turning, for those familiar with the game. I was a healer and used Healbot to let me click on player names to cast healing spells. Thus, I preferred to have my mouse free for this and used the keyboard for turning, which was minimal.