Bad metaphor: There is no evidence for Dvorak's technical superiority to QWERTY, neither is there for Esperanto over other languages.
Esperanto isn't intended to be superior. It's value is on it being equally foreign yet approachable for all the salient parties and therefore a conceivable acceptable neutral turf for everyone to share.
Ironically, the case for Dvorak keyboards is kind of the opposite: QWERTY was intentionally designed to avoid jams, which if anything biased towards making it more difficult.
It's not so much technical superiority as having a design objective that is more appropriate for the problem space.
One can similarly argue about whether "QUEL" is really technically superior to "SQL", but the design objective is (at least as perceived by the author) better aligned with the solution space.
This was not even attempted; Esperanto is a Romance language. Unless you think the only salient parties are Spain, France, Portugal, Italy, and Latin America, this "value" does not exist and was not a goal.
And it was pretty much a goal of its creator to be both familiar and foreign for different european language families, as he had experienced division in Poland between speakers of those different families and wanted to have something more universal to gather them all together.
Esperanto has been described as "a language lexically predominantly Romanic, morphologically intensively agglutinative, and to a certain degree isolating in character".[74] Typologically, Esperanto has prepositions and a pragmatic word order that by default is subject–verb–object. Adjectives can be freely placed before or after the nouns they modify, though placing them before the noun is more common. New words are formed through extensive prefixing and suffixing."
Minor quibble that this is not true (or at least strongly disputed).
https://www.smithsonianmag.com/arts-culture/fact-of-fiction-...
Outside Western Europe, Esperanto makes rather little sense. It's highly regular, which is nice — but, say, Japanese is also highly regular.
Today we can be tempted to frame it as european chauvinism, but that's just because of our expanded horizons as a global society. People who believes in esperanto in the early days would likely share the same feeling now
QWERTY isn't as bad as people make it out to be, and Dvorak isn't as good as people make it out to be.
There are keyboard configurations that are better than both, but nobody uses them because you'll never be able to use anybody else's keyboard.
I doubt that's the main reason, and it may be unwarranted as I say below. Personally, I thought it would take too long for me to be able to type as fast as in QWERTY. Fortunately, I was wrong about that too.
I learned the QGMLW optimized layout from Carpalx (linked above) about a year ago. I trained on https://keybr.com and then on https://typeracer.com for a few days and in less than a week I reached 70wpm. I stopped training shortly after and now I can usually reach 90-100wpm. Not particularly fast, but I'm not any faster in QWERTY, and I believe I could get faster if I trained more.
Even though I almost never type in QWERTY anymore, when I do I'm still just as fast as I used to be. I never learned to type in QWERTY "the right way", though, and I suppose this is actually what keeps me from confusing the two "modes". Whenever I try to keep my fingers on their "appropriate" keys (like a properly trained typist would), it's like my brain switches to "Carpalx mode" (since I did make an effort to use the right finger positioning to learn it). It's kinda like switching between thinking in my native language and English - I can think in both, but it doesn't "feel" the same, and I'm more likely to confuse the two where they overlap more. Pretty interesting, really.
I can still type qwerty but I'm not very fast at it (I never was).
People always rationalize their inability to change. Those who made a step knows both rewards and cost. It was worth it hundred times.