[MAJOR ENDWALKER/SHADOWBRINGER SPOILERS] On the introduction of dynamis.

[Cleretic]

It's flawed to simply attribute all previous phenomena to Dynamis. For example the Totentanz is explicitly described as an aetheric reaction, and in Omega WoL's varying powerlevel is ascribed to subconsciously limiting your aetheric output and having inconsistent and therefore unpredictable performance, which as a machine Omega cannot comprehend.

When we learn about akasa from Nidhana, it is specifically mentioned as a very esoteric field without a lot of study around it, so I can completely understand a group of people largely without scientific background--like, say, a dancer's troupe--not quite getting all the facts right. The fact that pretty much every single thing about the Totentantz checks out except that suggests to me that they were dealing with a dynamis situation and just mislabeled a few things. Personally, I think the Totentantz was actually deliberately written to be a dynamis thing, because the writers clearly already had the ideas laid out internally, and things just line up way too well. In fact I'd consider discrepancies to be less 'proof that it's not this thing' and more suggestion that maybe the plans changed a tiny bit in the time between expansions. It'd also be far from the only time when they play with a concept in side content that would later appear fully-formed in the MSQ; consider the designs for what would go on to be Sin Eaters in Amdapor Hard, or Eureka being what can only be described as a 'creation magic primal' in Stormblood.

And as for Omega... while that I personally don't think was exactly a Dynamis Thing (I think more plausible about Omega is that Omega's very bad at separating fantasy from reality, and is so muddled by it that it can't even parse combat very well), I do think that if there's any 'genius intellect' in the game that would definitely suck at seeing dynamis, it is absolutely Omega's people. They are phenomenally bad at understanding emotions, not to mention barely having any themselves, I'm fairly sure it's straight-up impossible for them to detect an emotionally-influenced energy like dynamis.