I used to think exactly the same way. In my opinion, this is an excellent question.
The thing is, I've been actually doing a similiar (not exactly the same) version of the pulse feast ever since the pulse FAST protocol came out, and stumbling into this has really changed the way I eat.
I found great success in the 6 meal a day (365 days/year for DECADES) route....it was tried and true by many aspiring muscle/strength builders. It simply works, especially for those who are somewhat ectomorphic to begin with.
It is my opinion (and I believe it is stated in the articles) that the birth of these type of "liquid" diets come from those who are actually more ectomorphic and were desperately seeking a new way to deal with the issue of their disposition to deposit nutrients into fat rather than muscle. The V-diet was the precursor...and came the pulse fast. And now, the pulse feast.
My physiology is predominantly ecto-mesomorphic, so I need (or thought I needed), a whole lot of calories and nutrients to gain or sustain my muscle building endeavors. Since reading about the pulse fast and attempting it (and FAILING at even being able to go through with it), like I mentioned, I stumbled upon a version of the pulse feast. I have to state: the pulse feast (incarnation I used that is...that's the only experience I have so far) is the way to go for me these days. I feel much "tighter", my already relatively low bodyfat amount is less (subjectively....I will be embarking on my own more scientific experiment on this shortly), and I am not losing lean tissue nor strength. Quite the contrary...I believe (again subjectively for now) I am gaining lean mass and my energy and power levels are greater.
So, where I thought these types of diets are only perhaps really good for ectomorphs, I think I was wrong.
A speculation I have but can't really prove, is that I might have had to eat the 6 meals/day for my gains simply because my body's ability to process (digest) food might not be as efficient as I thought. So, if I consume 350 grams of protein total in my 6 meals, I might have only really been efficiently absorbing 200 grams (plus or minus whatever).
With the intake of something like MAG-10 (or Metabolic Drive Muscle)which is "advertised" as being easier to digest (with the claim that easier to digest means more nutrient efficient) during something like the pulse feast, I might now be getting at least that 200 grams or more into my bloodstream and into my cells. Again, I can't prove it....but I know how I feel doing this as compared to how I felt before.
Just laying out my thoughts here. I still think this is an excellent question you've posed and stating my present subjective results.