See, I don't mind at all. They clearly stipulates Dynamis doesn't interact with aether, and so its effect are very slim.
Compare it to Dark Energy, which is pretty much a similar concept of expansion energy : we only literally supposed its existence 23 years ago. Neutrinos, which barely interacts with matter, has only been speculated around 1930 and discovered in 1956.
Why would people who research aether, which can explain most things, suppose there's anything else?

Thing is, we discover and theorize about new form of matter / energy quite often, and some we probably never heard about. What's to say most of the summoning that took place in Eorzea somehow used a bit of Dynamis to increase the effects?
We know Aether and Dynamis can interact, since Meteion was created by a being that cannot interact with Dynamis, just like the Elpis flowers that were happy accidents.

As for Limit Breaks, perhaps Elidibus did the same as Hermes or that Elpis maker, or perhaps it's just aether but what Meteion noticed was that we channeled Dynamis in addition to Aether when surviving an attack that would otherwise totally obliterate us, against all odds.
On a sidenote, my headcannons about LB is that we use the aether residues generated by spells and skills over the duration of a fight, and channel it into one big effect