From my limited reading, the major limiting factor is the opacity of the ink at normal application levels
That's really not the problem for most processes if you're using Epson Matte black ink or something similar, with which you can easily hit logD 2.5 and higher. There are also very, very effective UV blocking dye-based inks (>3.0 logD) that can be 'plugged into' any printer that uses refillable cartridges.
The problem is not so much that the blocking ability is too limited (which it can be on some dye-based printer systems, but that's a different matter). The challenge is getting good tonality without posterization, coarse grain-like patterns and an overall 'rough' look to the image.
In online writings the issue is often smashed flat into one of covering power. There are still many dye-based printing systems around that indeed offer very limited UV covering power, or transmission density in general. However, pigment-based printing systems have been used for digital negative creation for well over 15 years now, so the covering power problem was basically overcome long ago - provided you have the willingness and budget to buy into the technology. This leaves the real challenges, which are not about raw covering power at all, but 'simply' about getting good prints. If you compare prints made from in-camera silver gel negatives to prints made with digital inkjet negatives, it's really quite challenging to get the same impression of smooth tonality on the latter. The same fine detail rendering is out of the question to begin with since inkjet just doesn't come close to the resolving power of silver gel film, but you have to look pretty up close & personal at a print to be able to see that. The tonality problem is much more profound, especially on processes that are inherently capable of very smooth gradations like most of the metal-based processes on fine-textured or smooth surfaces and processes like carbon transfer.