This is specious reasoning. There's a process that turns both of us into mulch (it involves a woodchipper), but you shouldn't attempt that process based on the inference that a reverse process (a mulch-to-human machine?) must therefore exist.
It was not an "acknowledged thing." It was a bloody, brutal affair. Men fighting for titles is probably the one thing that measures up to religion in terms of lives lost.
And all of this before refuting the central point: the duke of some random duchy in 1305 had no "increased social legitimacy" in any way that matters to contemporary humans. He was able to petition whatever king he served, and he could rule over his own land insofar as someone with a bigger army didn't mind. It is, on face value, ridiculous that we're discussing this as a viable state of affairs.
I think you are making the mistake of reading too hard into these writings and somehow managed to invent a meaning in it. The reality is unfortunately as simple as that these people imagine they would get to be kings and rule over everyone. The philosophy dropout verbose word vomit is required to obscure this simple and obviously idiotic point because of course why would anyone pay attention to it otherwise.
Again, power is a pervasive feature of any complex society. Do you pick formal and legitimized power, or power that's completely illegitimate and shorn of any formality?
> Making Peter Thiel a Duke isn't going to help.
If you have some sort of proceedings to make Peter Thiel a Duke, there might also be ways to strip him of his title for cause. Which might actually increase the public's collective power over acknowledged elites, and that without any resort to the more physical means you alluded to in your comment. After all, it would be more of a routine quasi-criminal sanction than a social revolution.