On reading the original post what clearly comes to mind first are some of the obvious limitations of collodion and wet plate processes. While they are timeless and beautiful they are fraught with difficulties that nearly always limit them to a studio controlled situation. With these we tend to see the simplest of still life's and at best, some beautiful portraits. Robb Kendrick has done some masterful and beautiful work in this venue. So also has Quinn Jacobsen. Their work stands apart because their subjects are interesting. Very real folk if you will.
To a lesser degree ULF / Platinum also has some limitations. You need a good negative with perfect range for the processes usually using very vintage equipment unless you're a millionaire. All of these add up to let's say less chance of success than a guy with a Nikon.
Mostly though the problem is the subjectivity of the viewer. I would challenge Grant and others with a reciprocal argument. Are you unwilling to make the effort to move to ULF and therefore hiding behind a sour grapes argument that "I'm not going there because it's just a bunch of folks making boring pictures with wild notions of mastery only because it's a big expensive camera etc." No less valid than your original assumptions.