It's always hard for me to "get with the program" of "doom and gloom" over this Camino modernisation push -- except in certain particular cases, egregiously bad, where the original pathway is replaced by a thick layer of naked concrete.
Very often, the crushed rocks versions of these paths are among the easiest ones to hike on, which I liked in my younger days when I was very fast because I could really eat up the K on such surfaces, and I like in my present situation of being a handicapped person because of the more reliable and less risky surface they provide.
As for tiny little footpaths, they could and can sometimes be OK for me for both purposes, old and new, but that would depend entirely on the quality of the overall terrain, so that's hardly a given ; however, in most cases, these paths used to slow me down and so led to longer hiking days, they nearly always have a risk of being nasty, wet, and muddy, and today from my handicap they can sometimes even be difficult for me to walk at all, so that quite frequently such paths can force me to go and hike on the tarmac alternative instead.
Muddy paths can also be particularly bad for me personally due to my heavy body and size 14 boots.
I'd agree that in some cases, and particularly in drier areas like the Languedoc or much of Catalonia, or Castilla y Léon, it is very often better to leave the Camino relatively "unmodernised" where it still exists in an "original" state, in the spirit of "if it ain't broke, don't fix it" ; but elsewhere, well, it simply isn't any default "truth" that such "original" states must be superior to the modernised ones.
And particularly not in places with such heavy rainfall as Galicia, which can turn any "natural" pathway into an impraticable length of mud pits, flowing streams, and mud-bottomed depths of rainwater.
Of course there's never been that much "natural" about the Camino in the first place, after it began all those hundreds of years ago along the pathways of the old network of Roman roads. It's mostly where nature has reclaimed the old Roman and mediaeval paved roads that the original Camino routes are now dirt tracks.
And as for the "holoways", in my lengthy experiences several times through France on multiple different routes all over the country, and in Spain on the Francès, Aragonès, and Catalan, I've only rarely seen those having been "destroyed" by anyone or anything, but frankly in the vast majority of cases it is through massive degradation by heavy farming or logging machinery ; not resurfacing for hikers. And where they have been resurfaced, in my experience it's mostly for those machines and against any more destruction by them, little to do with any hikers.