A great essay! It is worth noting that such ideas are woven into certain constitutional traditions called 'dignitarian' in constitutional law, which take their inspiration from the first and second articles of the Federal German Grundgesetz or Basic Law, which hold that: "(1) Human dignity shall be inviolable. To respect and protect it shall be the duty of all state authority. (2) The German people therefore acknowledge inviolable and inalienable human rights as the basis of every community, of peace and of justice in the world."
But even before the development of the Grundgesetz in 1949, I think that the same thing is also what was (and still is) meant by Fraternité in the tricolon of the successive French republics: Liberté, Égalité, Fraternité.
As the author suggests at one point, in Anglophone societies, the right speaks of Liberty and the left speaks of Equality, but seldom does anyone seem to mention Fraternity (or Dignity, as I think we might say if starting from scratch like the Germans, though I think Fraternité goes a little bit further but is of course hard to render in non-gendered terms.)
In any case, without Dignity, or Fraternité, the result is a deracinated political discourse in which, among other things, it becomes hard to defend Equality--because, why?--and in which Liberty turns into 'licence', to employ an even older formulation from the days of Locke and Milton.
Such are the deficiencies of Anglophone liberalism broadly speaking and in the British sense of the word 'liberal', which is more inclusive than the US sense of the word and also more accurate: a political order into which the conventional Anglophone centre-left and centre-right both fit, and not just the centre-left.
Lacking Dignity/Fraternité, the entire liberal order (so defined) suffers, as the French would also say, from "incivisme."
Like the addition of salt or umami to a bland dish badly in need of it, the addition of Dignity/Fraternité immediately transforms an insipid Anglophone liberalism into something similar but more robust, which some people call civic-republicanism (see Liberalism and its Critics, edited by Michael J. Sandel.).
As its name suggests, civic-republicanism also gives greater protection for grassroots urban democracy and public spaces of every kind, both physical and communicational. Again, under liberalism, the left supports these things, but once again, it has a hard job answering the question why?, other than in terms of policy-wonk arguments that don't really inspire anyone to the barricades.
(Civic-republicanism is not, of course, to be confused with the US Republican Party in its present incarnation, which doesn't seem to be too liberal either.)