Ok let's start with this Asus marketing image.
First of all the signal from controller to doubler is single, but then it is split by the doubler and sent to each phase.
In the Asus system, the single phase consists of multiple stages, the signal from the controller is split from a single source and fed to each stage in the phase. There is NO balancing beyond the attempts to make each stage naturally balanced, but due to mass assembly and the desire for boards not to be $2000, the stages uses components that are +/- 5-20%.
How doublers work and can balance...
An intelligent controller can balance after dumb doublers. By reading how each phase is handling the load and actually telling the dumb controller to pull or push.
A smartish controller feeds a smart doubler the PWM signal. The smart doubler starts out just feeding both phases the same signal but monitoring both. Phase 1 is running a little harder than Phase 2, so the smart doubler actively shortens the PWM signal to one phase and can leave the other alone of lengthen it.
The Asus system... Well it's got stages so umm... Can't do that. It's faster because it's just running straight phases, the differences are incredibly small though.
How does load balancing work...
One doublers, you can actually shut down phases if you want.
On stages you are limited to actual phases. So you are often incredibly limited in having any phases powered down because the power specifications will often have minimum phases operating and wake up times.
Asus also tends to use older controllers that they rebadge and use for many years. So this has the advantage of being way cheaper, because you don't need fancy controllers and/or fancy doublers, so the savings can be passed on to someone... LoL
Marketing vs lying...
Asus tries very hard to using marketing spin to say parallel stages = phases. It's a straight up lie.
The truth...
1 phase and 2/3/4/5/or 6 parallel stage
= 1 phase
It's just that one phase is wider and has redundancy built in. Each stage will topple over and should naturally balance as loads increase. Though it does mean bad things can happen if a stage fails, all that load suddenly gets rammed through the other stage and the controller doesn't know. Which is another disadvantage, the controller only sees the phase, so as long as one stage is still functional it'll keep on keeping on.
Comments on the rest...
I really like the article and all of the in-depth information in it is the kind of stuff I love.
Also did EK provide you the half cover stuff about blocks? They did make an infamous TR1 block that was a massive failure because it was just an AM3 cold plate mounted under a TR1 mount...
There are lots of blocks and AIOs that do proper full cover Threadripper plates. That part felt kinda like it was trying to pot shot other sites and to push EK.
Just my opinion. I really enjoyed it overall but I'm sorry but your Asus board has an 8 phase VRM in reality. Please don't drink the Asus Koolaid it's bad for you.