Tom, Mackenzie did formulate his principles before WW1 and a striking aspect of his views is not only how early in his career he apparently developed them but how true he remained to them acorss his career.
Niall, as Rich says Pitreavie was mid-career for Mackenzie. Mar-teh (as in Par-teh) is the expert on the Pit so hopefully he will chime in -- the club got into a tussle with Charles Mackenzie over the construction of the course so perhaps that's at the bottom of your comment re the burns!
Bart, as Sean notes blindness then versus blindness now are on opposite ends of the spectrum. He wrote in unalloyed terms to communicate his ideas clearly but also to reduce misunderstanding; he was a teacher not just a philosopher. (It didn't hurt commercially that as Sean notes his ideas, being different, set him apart in the field.)
Who knows? Perhaps if Mackenzie came back today and saw blindness had disappeared only to be replaced by a different insipidity, he might start banging on about the blandness of modern courses and push for a return to blindness as a restoration of the "spirit of adventure," something to generate an emotional response.
And Mackenzie wasn't right on everything else. He violated his principles here and there, as he would have to. Not only blindness, but not routing returning nines, failing to give the weaker player a way to play a hole, etc etc.
But he was right a lot more than he was wrong, and he was right on the big things, like the ideal being enjoyable, exciting and challenging for all, not just a few. (He was Isaiah Berlin's hedgehog in that respect.) Blindness cuts both ways in that regard: it can create challenge and enjoyability for many, but it can force a shot beyond the ability of weaker golfers.
All IMHO.
Mark