I've been slowly making my way through White & Zainasheff's Yeast(y) tome; this topic comes up at page 75.
Long story short, adding enough O2 leads to a faster fermentation and improved attenuation. 8-10ppm is the target for most wort, and shaking only gets you in the high 2s.
Not saying anyone's process is wrong, especially if you're satisfied with the results, but why leave anything to chance? A healthy pitch is just the start. What about the rest of the race to FG?