Zach,
It's hard to speak for why other coaches promote the patterns and explanations they do. Most never show their work on how they got to the conclusions they did, so we have to just take their advice at face value. On that note, I can't really understand the argument to "not work on separation". I could support the idea that proper separation is hard, and consciously focusing on it might not produce it, so if you do a separation drill you have to monitor other pieces simultaneously. But it's much easier to explain why something is bad for everyone rather than trying to explain the nuances and how it could apply to some and harm others.
A couple thoughts. Just because transition is faster than the blink of an eye doesn't mean you shouldn't train it. It means you have to train it to be reflexive/automatic. "A single blink lasts for approximately 0.1 to 0.4 seconds, a duration so brief it's often described as a fraction of a second." The downswing is about .25 seconds.
By that logic you couldn't train anything in the downswing. Not what I suggest, or what they suggest. Seems a little hyperbolic to advise you can't train anything because it's so fast.
Second thought. I think the wipe is an interesting move. If you started with the puzzle that you wanted to create a high level of speed but with maximum control, how would you want to use your shoulders? I think it would lend itself to the wipe, but that type of shoulder motion is really hard to measure (impossible currently from what I've heard), so if your whole system is based on measurements, then you might be unaware of some of these keys.
Reminds of one of my favorite quotes, "follow those who seek the truth, run from those who've claimed they found it". I'm still searching.
Happy Golfing,
Tyler