I say it all the time - work hard and you will get stronger. I rarely ever criticize another coaches methods and when I do its generally in my own head.
I have written plenty of training plans based on volume calculations as a way to manage fatigue. Hell Sheiko does it like that.
So to compare the two in regards to managing fatigue:
A common issue I would run into with clients was the sudden and immediate need for a deload. It's tough to predict when each individual starts to burn out. At the same time you don't want to go with a deload scheduled at certain intervals because maybe they don't need it and now you lose progress.
With RPE you can still TRACK the volume like you always have, but the deload is almost built in by the auto regulation of fatigue.
Now this isn't to day it is a perfect system. The coach or athlete should still keep a log and patterns may develop.
Say you notice the deadlift in week 1 thru three was always in excess of 600 for triples and sets of 5. Then suddenly you start seeing 500's and chronic complaints from the athlete in the notes about "just didn't have it today." That would mean a deload would be prudent.
In other cases the deload should be stuffed in when transitioning. For example I have @
_3M_ starting a run up to a November meet. He was making insane progress as you can see in his log. But I just wanted to keep him fresh and healthy.
I guess my point is rather than using volume alone to bring about them gains what if you just kept bringing the athlete shy of the brink and had them ride that out while slowing down when they need to?