Yes, I agree there. The Zone system leaves a certain leeway in visualization in that one man's Zone 2 mau be another man's Zone 3. A numerical scene brightness range visualized in terms of a numerical paper density range, and a contrast index obtained by a least-squares fit of a straight line to a definite portion of an H&D curve are not easily personalized. It is a little more difficult to impersonalize the nuances due to other than random deviations from the straight line, but we use terms like long toe, etc.
It is certainly easier for me to convey the results of my tests to you and vice versa using BTZS numbers, especially if I can provide the H&D curves.