We seem to be in agreement that a dye image can improve the printing properties of a negative. (What is the Pyro stain if it isn't a developer produced dye?)(posted 8762 days ago)
Whether that dye image is a crude stain from Pyro or a properly controlled dye-coupler reaction appears to be where we differ.The permanence of colour negative film is very good. I have C-22 processed negatives going back over 30 years which show no sign of fading, and C-41 appears to be even more stable. In any case, the stability of the dye-couplers used in colour film is compromised by the need to render colour accurately. If more-or-less any old image colour would do, then the dye(s) could be made much more permanent.
C-41 is available worldwide, PMK isn't, and C-41 can also be bought in kit form, for those who want to push or pull the development. The bleach could also be left out to leave a 'proper' silver image.BTW Pyro-Metol developers have been around for far longer than PMK. Ilford published a formula called ID-4 in 1960 (this is the publication date of the formulary I have, the formula itself is probably much older).
Things move on, and times change, we should embrace technical change and not cling to the past. Modern colour films use things like DIR couplers (development induced restraining) to tailor the characteristic curve of the film. This a far more sophisticated technique than could ever be produced by a simple staining process.
I used to mix my own developers from raw chemicals and experiment with darkroom procedures a lot, but I now consider this was a complete waste of time. I should have been taking pictures, not weighing chemicals, because no esoteric formula will turn a mediocre picture into a good one. A good picture developed in D76 will still beat a bad 'un developed in Pyro or anything else.