It is interesting to me that this sentence almost perfectly describes DNC and RDM gameplay. Random Procs completely determine what skills you use and there is no set rotation. The line I quoted above suggests that these types of systems should theoretically "increase the mechanical skill cap." In practice, we see that this isn't true for FFXIV. DNC and RDM are considered two of the easiest jobs to play at a high level in the game. Perhaps, if the jobs had more complex proc mechanics, instead of the mindless 50% chance procs they currently have, your comment would line up with what we see in the game. It's also interesting that you used DRG and MCN gameplay to argue your point, when these are also considered to be some of the simplest jobs to master.
I don't really agree or disagree with the premise of your argument, I just thought this was interesting.